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LIBRARY OF CONGRESS, 



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UNITED STATES OE AMERICA. 



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Elementary Physiology and Hygiene 



THE HUMAN BODY 



ITS HEALTH 



A TEXT-BOOK FOR SCHOOLS, HAVING SPECIAL REFERENCE TO 

THE EFFECTS OF STIMULANTS AND NARCOTICS 

ON THE HUMAN SYSTEM 



BY 

WILLIAM THAYER SMITH, M.D. 



ASSOCIATE PROFESSOR OF ANATOMY AND PHYSIOLOGY IN DARTMOUTH 
MEDICAL COLLEGE 



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Is 










Copyright, 1884, by 
IVISON, BLAKEMAN, TAYLOR, & COMPANY 

PUBLISHERS 
NEW YORK AND CHICAGO 

\ 



EXTRACTS FROM RECENT LEGISLATION 

AFFECTING THE PUBLIC SCHOOLS. 

STATE OF MINNESOTA. /3>G>"""\^ 
Section 1. That all school-officers in the State may introduce as part 
of the daily exercises of each school in their jurisdiction, instruction in 
the elements of social and moral science, including . . . self-denial, 
health, purity, temperance, cleanliness. . . . 

STATE OF MICHIGAN. 
Sect. 15. The district board shall specify the studies to be pursued in the 
schools of the district: Provided always. That provision shall be made for 
instructing all pupils in every school in physiology and hygiene with 
special reference to the effects of alcoholic drinks, stimulants, and nar- 
cotics generally, upon the human system. 

STATE OF NEW HAMPSHIRE. 
. . . And in physiology and hygiene, with special reference to the effects 
of alcoholic drinks, stimulants, and narcotics upon the human system. 

STATE OF NEW YORK. 
Provision shall be made by the proper local school authorities for in- 
structing all pupils in all schools supported by public money, or under 
State control, in physiology and hygiene, w T ith special reference to the 
effects of alcoholic drinks, stimulants, and narcotics upon the human 
system. 

STATE OF OHIO. 

To the board of education the State has primarily intrusted the respon- 
sibility of seeing that her teachers are grounded in all the dangers that 
beset her youth, and that they are disposed to arm their youth with the 
requisite knowledge, convictions, and resolution to guard against these 
dangers. The effect of alcohol on the brain and nerves — its innate ten- 
dency, like all narcotic poisons, to enslave the appetite, and lead to excess 
and ruin — should be clearly made known to every youth while in school. 
— From notes explaining school-law. 

STATE OF VERMONT. 
. . . And elementary physiology and hygiene, which shall give special 
prominence to the effects of stimulants and narcotics upon the human 
system. . . . 

*** Several other States have passed similar laws. 



PREFACE. 



In making this little book, I have tried to give to the 
student a definite impression, in outline, of the structure 
and functions of the human body. To this end I have 
tried to omit all statements that would confuse the picture 
by overloading it, and all statements that could not be 
understood by those who will be its most numerous read- 
ers. I have not told them, for example, that the re-action 
of the saliva is alkaline, and that of the gastric juice acid, 
because for many of them that statement would have no 
meaning. I have not mentioned the names of many of 
the muscles, because it is difficult and unnecessary to 
remember them. 

The laws of hygiene are given in connection with the 
facts of anatomy and physiology from which they are 
derived. Learned in this way, they will remain in the 
mind as guiding principles, and not simply as the dicta 
of authority. 

In treating of the effects of stimulants and narcotics, I 
have endeavored to set forth facts which are susceptible 
of abundant proof, and which are of the most importance, 
practically, to those for whom this work is designed. 

WILLIAM THAYEK SMITH. 

Hanover, N.H.. August, 1884. 



CONTENTS. 



CHAPTER I. 

PAGE 

Definitions ...«,.. 13 

Anatomy, Physiology, Hygiene. 



CHAPTEE II. 

The Bones and Joints , . . . . 17 

Section I. Uses of the Bones. Two Cavities in the Body. Num- 
ber and Distribution of Bones. — Section II. Bones of the Head 
and Trunk. — Section III. Bones of the Upper Limb. — Section 
IV. Bones of the Lower Limb. — Section V. Structure of Bone. 
— Section VI. Chemical Composition of Bone. — Section VII. 
The Joints. Parts which compose a Joint. 

CHAPTEE III. 

The Muscles » 40 

Section I. Voluntary and Involuntary Muscles. Tendons. Apo- 
neuroses. Number of Muscles. — Section II. Properties of 
Muscle. — Section III. Structure of Muscle. — Section IV. Mus- 
cular Exercise. Reasons for its Value. Ends to be sought 
by it. Cautions. Muscles of Expression. — Section V. Effect 
of Alcohol on the Muscles. 



CONTENTS. 



CHAPTER IV. 

PAGE 

Work and Waste. — The Blood 50 

Section L Wear and Repair. Sleep. — Section II. Materials for 
Repair. Air. Food. Water. — Section III. The Blood. Red 
Corpuscles. White Corpuscles. The Plasma. Coagulation. 
Loss of Blood. Causes of Impure Blood. 



CHAPTER V. 

The Circulation 60 

Section I. Organs of Circulation. Arteries. Capillaries. Veins. 
— Section II. The Heart. The Pericardium. The Auricles. 
The Ventricles. The Tricuspid Valve. The Pulmonary Ar- 
tery. The Pulmonary Veins. The Semilunar Valves. The 
Mitral Valve. — Section III. Action of the Heart. The Heart 
a Double Pump. The Lesser Circulation. The Greater Cir- 
culation. — Section IV. Sounds of the Heart. — Section V. 
Arteries. Veins. Capillaries. Rapidity of Blood-Current. 
Points in which Arteries and Veins differ. — Section VI. The 
Pulse. What the Pulse tells. — Section VII. Variations in 
Blood-Supply. — Section VIII. Effect of Alcohol on the Circu- 
lation, 

CHAPTER VI. 

Food and Water, Stimulants and Narcotics 77 

Section I. Definition of Food. Elements in the Body. The 
Work of Plants. Flesh-eating Animals. Vegetable-eating 
Animals. Milk. Meats. Starchy Foods. Graham Flour. 
Sugar. Fat. Cooking. Mineral Substances. Water. Eat- 
ing and Drinking Habits. — Section II. Tea and Coffee. To- 
bacco. Opium. Alcohol. Chloral.. 



CONTENTS. 



CHAPTER VII. 

PAGE 

Digestion and Absorption. — The Lymphatic System . ...... 98 

Section I. The Alimentary Canal. Mucous Membrane. Di- 
visions of the Alimentary Canal. Definition of ''Digestion." 
Pancreatic Juice. Emulsions. Chyle. Lacteals. Work of 
the Muscular Walls of the Canal. The Teeth. The Sali- 
vary Glands. The Stomach. The Gastric Juice. The Liver. 
The Pancreas. The Digestive Apparatus. — Section II. Ab- 
sorption. Villi. — Section III. The Lymphatic System. Tho- 
racic Duct. Lymph. Lacteals. — Section IV. Hinderances to 
Digestion. — Section V. Effects of Alcohol on Digestion. 

CHAPTER VIII. 

Respiration and the Voice 121 

Section I. Air. Respiration. Composition of Air. Nitrogen. 
Carbonic-acid Gas. Oxygen. — Section II. Structure of the 
Lungs. — Section III. The Air-Passages. The Nose. The 
Nerves of Smell. Breathing through the Nose. Snoring. 
The Throat, The Larynx. The Trachea, The Bronchi. 
The Bronchial Tubes. — Section IV. Breathing. Process De- 
scribed. — Section V. Changes in the Blood. — Section VI. Waste 
Matters given off by the Lungs. Changes in the Air. Venti- 
lation. — Section VII. The Organs of Voice. Cultivation of the 
Voice. 

CHAPTER IX. 
The Nervous System 143 

Section I. The Brain. Cerebrum. Cerebellum. Medulla. Con- 
volutions. The Spinal Cord. Membranes of the Brain and 
Cord. Gray Matter. White Matter. Nerve-Cells. Nerve 
Fibers. — Section II. Action of the Nervous System. Reflex 



CONTENTS. 



CHAPTER IX. — Concluded. 

PAGE 

Action. Winking. Coughing. Sneezing. Sensory Fibers. 
Motor Fibers. — Section III. Seat of the Higher Faculties. — 
Section IV. Nervousness. Habit. Exercise for the Brain. — 
Section V. Effects of Alcohol on the Brain and Nervous 
System. 

CHAPTER X. 

The Skin.— The Ear. — The Eye 156 

Section I. Structure of the Skin. Epidermis. Derma. Pa- 
pillae. Sweat-Glands. Perspiration. The Hair. Sebaceous 
Glands. The Nails. Uses of the Skin. Bodily Heat. How 
Heat is equalized in the Body. Clothing. How the Body is 
cooled. — Section II. Care of the Skin. Colds. Rubbing the 
Skin. Bathing. Cautions in Bathing. — Section III. The Ear. 
Description of its Parts. How we hear. Ear-ache. — Sec- 
tion IV. The Eye. Description of Parts. How we see. 
Causes of Trouble in the Eye. Too Long Sight. Too Short 
Sight. Causes of too Short Sight. Care of the Eyes. Color- 
Blindness. 

APPENDIX. 

What to do in Case of Accident . . . . , 181 

Fainting. Fits. Sunstroke. Shock. Fractures and Disloca- 
tions. Bleeding. Poisoning. Drowning. 

GLOSSARY 187 

INDEX 193 



LIST OF ILLUSTRATIONS. 



COLOEED ILLUSTRATIONS. 

Page 
General Representation of the Muscular System . . 38 

The Heart and Large Blood-vessels 58 

No. 

1. The Skeleton 15 

2. The Skull 19 

3. Section of the Backbone . 20 

4. A 'Vertebra 20 

5. The Thorax .21 

6. The Sternum 22 

7. Bones of the Upper Limb 23 

8. The Scapula 23 

9. The Humerus .24 

10. Bones of the Fore-arm 24 

11. Bones of the Hand 25 

12. Bones of the Lower Limb ....... 2G 

13. The Femur 26 

14. The Patella 26 

15. Bones of the Leg ......... 27 

16. Bones of the Foot 27 

17. Section of the Femur .28 

18. The Periosteum 29 

19. A Bone after soaking in Hydrochloric Acid . . 30 

20. Joints of the Skull 31 



10 LIST OF ILLUSTRATIONS. 

No. Page 

21. The Hip-joint 32 

22. The Shoulder-joint 33 

23. Back of the Lower Limb 41 

24. Biceps Muscle 42 

25. Fibers of Voluntary Muscle 43 

26. Fibers of Involuntary Muscle 43 

27. Red Corpuscles of Human Blood . . . . .53 

28. Red Corpuscles of Frog's Blood 53 

29. Representation of a Section of the Heart . . .62 

30. Semilunar Valves open 63 

31. Semilunar Valves partly closed 64 

32. Representation of the Greater and Lesser Circu- 

lations . 66 

33. Representation of the Arterial System ... 68 

34. Capillary Plexus 70 

35. Vein laid open, showing the Valves .... 70 

36. A Drop of Milk magnified, showing the Oil-globules . 82 

37. Alimentary Canal from the (Esophagus down. . * 99 

38. Incisor Tooth sawed in two 104 

39. Molar Tooth sawed in two 104 

40. The Salivary Glands 105 

41. Stomach Glands of a Pig 107 

42. The Liver, and other Organs of Digestion . . .108 

43. Villi of the Small Intestine Ill 

44. Villi showing Vessels Ill 

45. Lymphatics of Arm pit 113 

46. Lymphatics of Intestine . 114 

47. Lungs in Position 124 

48. Gills of an Eel 125 

49. Section of Lungs 126 

50. Section of Nasal Fossae 128 

51. The Chest, showing Diaphragm 131 

52. The Larynx 138 

53. Representation of the Nervous System . . . 142 



LIST OF ILLUSTRATIONS. 11 
No. Page 

54. Brain and Upper End of Spinal Cord, with Nerves 

coming from them 144 

55. Brain and Spinal Cord, with Nerves coming from them, 145 

56. Nerve-cells .146 

57. Nerves of the Arm 147 

58. Nerves of the Fore-arm and Hand 148 

59. Section of Skin 157 

60. Papillae 158 

61. Papillary Ridges in the Skin of the Palm, showing 

the Pores 158 

62. Sweat-Gland, with Capillaries surrounding it . 159 

63. Section of Skin showing Roots of Hair . . . . 160 

64. TnE Ear 167 

65. Bones of the Ear 168 

66. The Eye 170 

67. Section of the Front of the Eye 171 

68. Lachrymal Apparatus 172 

69. Muscles of the Eye-ball 172 



THE HUMAN BODT 



T 



CHAPTER I. 
DEFINITIONS. 



Section I. — 1. If we wish to study a machine, such 
as a clock or a steam-engine, we take it to pieces, and ex- 
amine each part separately. We inquire what each part 
is called, what it is made of, and how it fits in with the 
other parts. We then ask what is the use of each part, 
and how it works. Knowing these things, we understand 
the machine and its action. 

2. The human body, which is the most wonderful of 
all machines, is to be studied in this way. 

Anatomy names and describes its parts. It tells us 
their size, weight, shape, color, texture, and composition ; 
their position, and relation to other parts. 

Physiology acquaints us with the action of each part, 
and the work that it does. It tells us how it acts, when 
it acts, what makes it act, and what is the effect of its 
action. 

Anatomy may be studied in the lifeless body. 

Physiology must be studied in the living body. 

Anatomy is well known, because all the parts of the 
body have been carefully studied and described. 

13 



14 THE HUMAN BODY. 

Physiology is only partially known. There are some 
parts of the body whose use w r e do not know. In those 
parts with which we are better acquainted we find much 
that we do not understand. But many learned men are 
devoting their whole time to this study, and are con- 
stantly adding to our knowledge. 

By combining the teachings of Physiology with what 
we know by experience w T e construct the science of 
Hygiene. From its principles we derive rules for the 
preservation of health. 

Anatomy is a science of Structure. 
Physiology is a science of Function. 
Hygiene is the science of Health. 



QUESTIONS. 

Section I. — What is the natural method of studying the body? 
What does Anatomy tell us of the body ? What does Physiology 
tell us of the body ? Can Anatomy be studied in the living body ? 
Can Physiology be studied in the lifeless body? Which is most 
thoroughly known, — Anatomy or Physiology? Define Anatomy. 
Physiology. Hygiene. 



/ Parietal. 



Orbit. 

Inferior Maxillaiy. 

Cervical Vertebras. 
Scapula. 

Humerus. — 
Lumbar Vertebras 




Temporal. 



Clavicle. 



Carpus 
Metacarpus 



-Innominate. 



Pelvis. 



.Patella. 



^ Tarsus. 
j. Metatarsus. 
,,-Phalanges. 



Fig. 1. 



16 



THE HUMAN BODY, 



THE SKELETON. 



The Head, 28 Bones. 



Occipital (base of skull) 1 

Parietal (sides of skull) 2 

Temporal (temples) 2 

Frontal (forehead) 1 

Sphenoid (behind the face) 1 

Ethmoid (behind the face) 1 

Nasal (bridge of nose) . . 2 

Vomer (between nasal fossoi) . . . . 1 

Turbinated (on walls of nasal fossa) . 2 



Palate (back part of roof of mouth) 
Lachrymal (in orbit) .... 

Malar (cheekbones) 

Superior Maxillary (upper jaw) 
Inferior Maxillary (lower jaw) 
Malleus (in the ear) "\ 
Incus (in the ear) 
Stapes (in the ear) 






The Trunk, 52 Bones. 



Vertebrae 

Sacrum 

Coccyx 



(backbone) 



24 
1 
1 



Hyoid (in the neck) . . 

Ribs 

Sternum (breast-bone) . 



1 
24 

, 1 



The Upper Limbs, 64 Bones. 



Scapula (shoulder-blade) 2 

Clavicle (collar-bone) 2 

Humerus (arm-bone) 2 j Metacarpus (hand) 

Radius (fore-arm) 2 Phalanges (fingers) 



Ulna (fore-arm) . . . , 2 

Carpus (wrist) 10 

10 

28 



The Lower Limbs, 62 Bones. 



Innominate (hip-bone) 2 

Femur (thigh-bone) 2 

Patella (knee-pan) 2 

Tibia (leg) 2 



Fibula (leg) 

Tarsus (ankle, heel, instep) 
Metatarsus (flat of foot) . 
Phalanges (toes^ .... 



. 2 
.14 
*10 



THE BONES AND JOINTS. 17 



CHAPTER II. 
THE BONES AND JOINTS. 

Section I. — 1. The bones are the framework of the 
body. When joined, as in the living man, they constitute 
the skeleton. They serve three purposes: — 

1. They give the body shape and firmness of outline. 
The soft parts which cover them add grace. 

2. They act as levers by which the muscles attached 
to. them move the body. 

s. They protect important organs. 

2. There are two main cavities in the body formed 
wholly or in part by the skeleton; viz., — 

1. The cavity of the skull and spinal column. The 
skull contains the brain, and is a tight box whose walls 
are strong, and which is so shaped as to resist great press- 
ure. There are no openings into it except those small 
ones through which blood-vessels and nerves pass in and 

Suggestions to Teachers. — 1. Every school in which anatomy and 
physiology are taught ought, if possible, to have a human skeleton. Lack- 
ing this, the next best thing is to have the skeleton of some quadruped. 
The general resemblance will be sufficient to make it a good illustration of 
the text. If you have no complete skeleton, get dried bones, — beef-bones, 
mutton-bones, vertebra?, long bones, jaw-bones. Have them sawed in dif- 
ferent directions. Much can be learned from them. The differences be- 
tween dried bone and fresh, living bone must, however, be borne in mind. 
The experiments of softening a bone by maceration in weak hydrochloric 
acid for a few weeks, and of removing the animal matter by burning, are 
easily tried. 

2. The different parts of a joint can be shown in a sheep's leg. 



18 THE HUMAN BODY. 

out. The great opening at the base of the skull connects 
its cavity with the spinal canal, and is fully an inch in 
diameter. The other openings are very much smaller 
than this. 

The spinal canal is also well guarded by its walls, and 
by bony projections. It contains the spinal cord. 

2. The cavity of the trunk. This is divided by a 
horizontal partition, called the diaphragm, into two parts. 
The upper part is the thorax, or chest; and the lower, the 
abdomen and pelvis. 

The thorax is a bony cage formed by the backbone 
behind, the ribs at the side, and the breast-bone in front. 
It contains the heart and lungs. These organs need to 
be guarded against blows or pressure, but they are not so 
easily injured in this way as the brain and spinal cord. 
The thorax is, therefore, not so close a box as the skull. 
Moreover, it is needful that the walls of the thorax should 
be movable in order that we may breathe. The thorax 
is so made that it gives sufficient protection to the organs 
which it contains, and at the same time it can enlarge 
and contract. 

The abdomen is not as well guarded as the thorax. 
There is no bony wall in front; and the intestines are 
easily wounded, though they bear pressure and displace- 
ment much better than the heart and lungs. But if the 
abdomen were walled in front, like the thorax, we could 
not bend our bodies. For purposes of motion, and to 
permit the expansion of the intestines after a full meal, 
they are left partially unprotected. 

The pelvis (Latin, pelvis, a basin) is formed by the hip- 
bones and the sacrum and coccyx. Its contents are well 
guarded by those thick bones. 



THE BONES AND JOINTS. 



19 



3. There are 206 bones in the body : — 

In the head 28 

spinal column .... 26 " 



In the trunk 



I* . 52 



ribs 24 

sternum 1 

, hyoid 1, 

In the upper limbs 64 

In the lower limbs 62 

206 

BONES OF THE HEAD AND TRUNK. 

Section II. — 1. The skull is poised on the top of the 
spinal column, and contains twenty-eight bones. In the 
young infant they are 
loosely united, but in 
time many of them 
become welded to- 
gether so that they 
can not be separated. 
The lower jaw, and 
the small bones of the 
ear, are the only ones 
of them that are mov- 
able. Besides contain- 
ing the brain, the skull 
protects the organs of 
hearing, of smell, of 
vision, and of taste. 

2. The spinal col- 
umn, or backbone, consists of twenty-four vertebrae, the 
sacrum, and the coccyx. The vertebrae (Latin, vertere, to 
turn) are so called because they form an axis on which the 
body turns. They are irregular in shape, and consist of 




Fig. 2. 



The Skull. — 1. Frontal bone. 2. Parietal bone. 
4. Temporal bone. 5. Nasal bone. 6. Malar bone. 
7. Superior maxillary bone. 8. Lachrymal bone. 
9. Inferior maxillary bone. 



20 



THE HUMAN BODY. 



a body and an arch. They have projections called pro- 
cesses, to which muscles are attached. When they are 

joined in position, the arches to- 
gether constitute the spinal canal, 
and the bodies form a solid col- 
umn for support. Between the 
bodies are cushions of a tough and 
elastic substance called fibro-car- 
tilage. Each is about one-fourth 
of an inch thick, and is firmly 
united to the bone above and 
below. They serve as springs in 
the column, and allow a twisting 
motion. 





i**^ 2 



Fig. 4. 
A Vertebra. — 1. Body. 2. Pro- 
cesses. 3. Spinal canal. 



The sacrum is a wedge-shaped 

bone, which fits in between the 

hip-bones. 

The coccyx is the end of the column, and is a small, 

curved bone, commonly in two or more pieces, which arc 

united by joints. 



THE BONES AND JOINTS. 



21 



3, The spine in a baby is perfectly straight, and his 
back flat, As he grows and walks the spine becomes 
slightly curved backward in the region of the shoulder- 
blades, and forward at the waist. This is natural. But 
frequently the curve of the back becomes too great. The 
shoulders are drawn forward, and the chest flattened. 
This makes a stoop. It is caused by weakness of the 
muscles which sustain the back and head, or indolence 
and carelessness. It makes an ungraceful shape, and is 
injurious because it compresses the heart and lungs, and 
checks their free action. An erect posture and a full 
chest should be cultivated. To this end, the muscles of 
the chest and trunk must be kept vigorous by exercise. 

, 1st rib. 




The natural curves of the spine are forward and back- 
ward. A curve to one side is unnatural and a deformity. 
It comes from bodily weakness, lack of air and exercise, 



22 



THE HUMAN BODY. 



and from standing on one foot habitually, or sitting much 
of the time at a desk or table with one arm resting upon 
it while the other hangs down. 

4. The ribs and breast-bone with the backbone form the 
thorax. The ribs are twenty-four in number, twelve on 
each side. They are joined to the backbone behind. The 
first seven are called true ribs. They are connected with 
the breast-bone by the costal cartilages. The last five are 
called false ribs. They are not directly connected with the 
breast-bone. The last two false ribs are called floating-ribs, 
because their front ends are not joined to any bone. 

The costal cartilages are continuations of the ribs. 
Cartilage is more elastic than bone, and the wall of the 
thorax expands and contracts more freely for being partly 
cartilage. It is by this expansion and contraction that we 
breathe. Whoever has harnessed horses has 
noticed that they generally swell their chests, 
and manifest displeasure, when the girths are 
buckled tight. It interferes with their breath- 
ing, and so with their comfort. If we are wise 
we shall resist, as they do, any compression of 
our chests or waists by tight clothing. The 
elastic walls readily yield to pressure, and after 
a time become permanently misshapen. The 
heart and lungs are then crowded; and the 
liver is displaced, and encroaches on the other 
organs. Thus, a figure is acquired which is 
Fig. 6. neither beautiful nor healthful. 
the steknum. q The ste rnum, or breast-bone, is a flat, nar- 
row bone, about five inches long, which is in the middle 
line of the chest in front. The collar-bones and the car- 
tilages of the ribs are joined to it. 




THE BONES AND JOINTS. 



23 



6. The hyoid bone is a slender bone shaped like a 
horseshoe. It is situated in the neck just above Adam's 
apple, where it may easily be felt. The base of the tongue 
is attached to it. 



Section III. 



Shoulder, 



Arm.- 



BONES OF THE UPPER LIMB. 

1. The upper limb is divided by anat- 
omists into shoulder, arm, fore-arm, 
and hand. In ordinary language, 
we call all between the shoulder 
and the hand, the arm. In ana- 
tomical language, the arm extends from 
shoulder to elbow; the fore-arm, from elbow 
to hand. 

2. The bones A i 
of the shoulder are 
the clavicle, or col- 
lar-bone, and the 
scapula, or shoul- 
der-blade. The 
collar-bone is 
about as large 
around as a finger, 
and curved in 
shape. It extends 

from the upper corner of the 
breast-bone to the shoulder- 
blade. It braces the shoulder. 

3. The shoulder-blade is a 
flat, three-cornered bone, with 
projections extending from it, to 
which muscles are attached. At one corner is a smooth 




Hand J 



Fig. 7. 
The Upper Limb. 




Fig. 8. 
The Scapula. — 1. Processes. 2. 
Surface for shoulder joint. 



24 



THE HUMAN BODY. 



t 



l'l I 



surface slightly hollowed out, on which the head of the 

arm-bone plays. 

4. The arm-bone is called the humerus. It is a strong 
bone, about a foot long in a grown man. It 
has a round head, which plays on the joint 
surface in the shoulder-blade. Its low r er end 
is joined to the two bones of the fore-arm. 

5. The bones of the fore-arm are called 
the radius and the ulna. The 
radius is on the thumb side, 
and the ulna on the side of 
the little finger. The radius 
is joined to the humerus and 
to the ulna in such a way that 
it rolls over on the ulna, and 
turns the palm of the hand 
up or down. The ulna is 
so joined to the humerus that 
it can only move forward and 
backward. The radius is joined 
closely to the hand, and, when 
it rolls over the ulna, carries 
the hand with it. 

6. The hand is divided into the carpus, 
or wrist, metacarpus, or palm, and pha- 
langes, or fingers. 

7. The wrist has eight short bones, irregu- 
lar in size and shape. These are bound by ligaments into 
a compact bunch. They glide a little on each other. 
Though they seem to be put together without design, 
they are really shaped and joined in such a way as to 
give freedom of movement combined with strength. 



Fig. 9. 
The Humerus 



Fig. 10. 
1. The Radius. 
2. The Ulna. 



THE BOXES AND JOINTS. 



25 



8. The five metacarpal bones are slightly curved, so as 
to make a hollow in the palm. 

The phalanges are in three rows, and are so called be- 
cause they are like rows of soldiers 
(GTeek 9 p]ialanx, a body of soldiers). 

The thumb stands out from the 
rest, and can be made to meet the 
end of each of the fingers. This 
enables us to pick up and handle 
small things with great delicacy. 
None of the lower animals has a 
thumb like man's except a few of 
the apes, and theirs is not so per- 
fect for handling. It is his hand 
more than any other part, except 
the brain, that gives man his su- 
periority over them. Its skill and 
delicacy when trained are won- 
derful. Most of the work of the 
world is done in part with the 
hand. Very much of it could not be clone at all if man's 
hand were not as perfect as it is. 




Fig. u. 

The Hand. — 1. Carpus. 2. Met- 
acarpus, o. Phalanges. 



BONES OP THE LOWER LIMB. 

Section IV. — 1. The lower limb is divided into hip, 
thigh, leg, and foot. In ordinary language, the word leg 
means the lower limb from hip to foot. In anatomical 
language, the part between the hip and knee is called the 
thigh ; the part between the knee and foot is the leg. 

2. The hip-bone is so irregular in shape, that the old 
anatomists could not think of any name that suited it; 
and so they called it the os innominatum, nameless bone 



26 



THE HUMAN BODY. 



The two hip-bones come together in front. Behind 
they are separated by the sacrum. The cavity inclosed 
between them is the pelvis, or basin. 

3. The femur, or thigh-bone, is the 
longest bone in the body. 
It has a round head, which 
fits into a socket in the hip- 
bone. At its lower end it 
spreads out to make a broad 
surface for the knee-joint. 
It is slightly curved. 



Leg. 




Fig. 14. 
The Patella. 



Fig. 12. 
The Lower Limb. 



Fig. 13. 
The Femur. 



4. In front of the knee is 
a small bone, heart-shaped, 
which is called the patella, 
or knee-pan. 

5. The leg has two bones, 

the tibia (Latin, tibia, a flute) and the fibula (Latin, fibula, 
a shawl-pin). The tibia is a strong bone. It has a sharp 
ridge in front, which is called the shin. The tibia is 
joined to the femur above. The fibula is a long, slender 
bone. It is joined to the tibia above and below. The 
lower ends of these two bones are joined to the ankle- 



THE BONES AND JOINTS. 



27 



^Tarsus. 




bone of the foot. They can easily be felt, one on the 
inner, the other on the outer, side of the ankle. 

6. The foot consists of tarsus, metatarsus, 
and phalanges. 

7. There are seven irregular bones in the 
tarsus. They form the ankle, the heel, and 
the instep. 

The metatarsal bones form the "flat" of 
the foot, and part of 
the instep. There are 
five in each foot. 

The phalanges, 
fourteen in each foot, 
form the toes. 

8. The bony struc- 
ture of the foot is quite 
like that of the hand. 
The differences are 
such as fit it for its 
humbler work. Its 
inner side is arched, 
and the weight rests 
on the heel and the 
ball of the toe. The 
foot is strong and elastic, and should 
be dressed in such a way as not to 
distort its shape or check its move- 
But, while we wonder at and despise the Chinese 




Fig. 15. 

1. The Tibia. 
2. The Fibula. 



Fig. 16. 
Bones of the Foot. 



ment. 

practice in this regard, we treat our feet in ways as truly 
unreasonable. The shape of our shoes is determined, not 
by the design of Nature, but by fashion. They are often 
too tight. Almost always they are too short, and too nar- 



28 



THE HUMAN BODY. 



row across the toes. Consequently the toes of most grown 
people are squeezed together, frequently overlapping. 
The great toe naturally rests a little separated from its 
neighbor, and almost in a straight line with the inner 
side of the foot. If we make it turn in, its principal joint 
stands out prominent, and from the pressure becomes 
inflamed. A bunion is formed there. A corn is another 
painful result of pressure. 

The foot is a much-enduring member, and is useful, 
even though crippled. But grace and ease of movement 
are constantly sacrificed, and numberless miseries in- 
curred, for the sake of making the foot look small. 

Athletes and pedestrians long ago discovered the neces- 
sity of a shoe which gives freedom to the foot. Such a 
shoe is never tight. The heel (if any) is low and broad, 
and directly under the heel of the foot. The sole is as 
broad as the foot itself, and at least half an inch longer. 

STRUCTURE OF BONE. 

Section V. — 1. If we saw a long bone in two length- 
wise two things are noticeable: — 




Fig. 17. 
Section of the Femur. 



l. Its shaft is hollow. During life the cavity is filled 
with marrow. This consists largely of fat, and is a 



THE BONES AND JOINTS. 



29 



store of nourishment which helps to sustain the body 
when it is deprived of food. It has been proved by 
experiment, that a hollow shaft is stronger than a 
solid shaft of the same material and the same iveigltt and 
length. 

2. The bony substance of the shaft is hard and com- 
pact, The large ends, on the contrary, though they are 
not hollow, are filled with cells, and present a honey- 
combed appearance. It is desirable that the shaft should 
be slender and strong. Its substance is, therefore, very 
compact, It is desirable that the ends should be large, 
to give a broad surface for the joints. Their substance is, 
therefore, open. If it were compact, it would increase the 
weight unnecessarily. 

2. If we saw a flat bone in two, as one of the bones of 
the skull, or a short bone as one of the bones of the wrist, 
we shall find, that, 
while its shell is of 
compact tissue, its in- 
side is of the same 
honeycombed tissue 
that we found in the 
ends of the long bone. 

3. Bones are well supplied 
nerves. We can find in every 




Fig. 18. 
1. The Periosteum. 



with blood-vessels and 
bone one or more holes 
through which a small blood-vessel passes to the interior. 
A living bone is covered with a membrane called the peri- 
osteum. In this membrane is a fine net-work of blood- 
vessels, from which a countless number of little vessels 
pass directly into canals in the bone. These are called 
Haversian canals. They run through every part of the 
bone. 



THE HUMAN BODY. 



CHEMICAL COMPOSITION OP BONE. 

Section VI. — 1. Bone is about two-thirds mineral, and 
one-third animal, matter. The mineral matter is chiefly 
phosphate of lime. This substance makes more than half 
of the bone. The mineral and animal matter are closely 
combined, but they can be separated in two ways: — 

1. If we put a bone in a moderate fire, and burn it, it 
w r ill become porous and brittle, but w r ill retain its shape. 
The animal matter is burned out, but the mineral remains. 

2. If we put a bone in w r eak hydrochloric acid, and allow 
it to remain for a few w r eeks, it will become as pliable as a 
rope, and can be tied in a knot. The acid has eaten out 
all the mineral matter, but has left the animal matter. 
If a bone has too much mineral matter, it is brittle. 
This is the condition of the bones of old people, and some- 
times of younger 
persons. They 
break very easily. 
In the bones of 
children, on the 
other hand, the 
animal matter is 
abundant; and 4 
they will bend a 

Fi £- 19. good deal before 

they break. In 
the disease of children called rickets, there is so little 
mineral matter in the bones, that they are too soft. The 
legs become bowed, the head enlarges, and the whole 
frame gets out of shape. 

2, During childhood and youth the skeleton is assum- 




A Bone after soaking in Hydrochloric Acid. 



THE BONES AND JOINTS. 



31 



ing the form which it is to keep through life. It is pliable, 
and may be molded to healthfulness and grace, or to 
deformity. Nature should be allowed to shape it in her 
own way, and all habits of dress or attitude or movement 
that interfere with the natural outlines should be care- 
fully avoided. 

THE JOINTS. 

Section VII. — 1. The joints of the body with which 
w r e are most familiar are movable ; but most of the joints 
of the head-bones are like a 
joint in a table or chair. 
They are fixed. 

The joints between the 
bodies of the vertebrae have 
a little motion, but are not 
freely movable like the joints 
of the limbs. 

There are, then, in the 
body,— 

Immovable joints. 

Slightly movable joints. 

Freely movable joints. 

2. The movable joints are 
of various kinds. Sometimes 
the two surfaces only glide a 
little on each other, as in the 
wrist. Sometimes one bone moves on another, like a 
door on its hinge. The elbow and the ankle are of this 
kind. 

Sometimes a round bone fits into a round socket, and 
moves in all directions. The hip-joint is of this kind. 




Fig. 20. 
Joints of the Skull. — 1. Frontal 
bone. 2. Parietal bone. 3. Occipital 
bone. 



32 



THE HUMAN BODY. 



Innominate. 



PARTS WHICH COMPOSE A JOINT. 

3, In a joint there are — 

i, Two or more bones, each covered, where they come 

in contact, with a thin, 
smooth layer of cartilage 
or gristle. Cartilage is 
more elastic than bone, 
and serves as a spring 
in the joint. 

2. Ligaments which 
bind the ends of the 
bones firmly together. 
A ligament is a white, 
glistening band, very 
strong, and generally 
not elastic. When we 
examine it with a mi- 
croscope, we find that it 
is made of fine white 
fibers, lying side by side 
like the threads of a ribbon, only there are no cross- 
fibers. They all run lengthwise. 

3. The cavity of the joint has a thin lining, called a 
synovial membrane. This membrane gives out a fluid 
called synovia, or joint-water. This serves the same pur- 
pose that the oil we put in the joints of machinery serves. 
But while these need constant attention, and soon wear 
out, the living joint oils itself, and may be in constant 
use for seventy years or more without causing a thought 
in the mind of its owner. 

If, however, joints become diseased, they are very 




Femur 

Fig. 21. 
The Hip-joint. 



THE BONES AND JOINTS. 



33 



painful. They sometimes become enlarged and stiff 
misshapen. 

4. The joints of young chil- 
dren bend very freely : as they 
grow older, they become less 
flexible. Some have "looser" 
joints than others. Those pub- 
lic performers who can twist 
themselves into marvelous 
shapes, are persons, who, by a 
course of training begun early 
in life, have gradually stretched 
their ligaments. 

5. Ligaments are tough, and 
not easily hurt; but when we 
do "sprain" a joint, which 
means that w r e have torn or 
overstretched its ligaments, they recover slowly. 



and 




Fig. 22. 
The Shoulder-joint. 



QUESTIONS. 

Section I. — 1. What is the skeleton? What three purposes does 
it serve? Can an animal body destitute of bones move? If so, in 
what way ? 

2. What are the two main cavities formed by the skeleton? 
How are the skull and backbone especially fitted to protect their 
contents? What are the two main divisions of the cavity of the 
trunk ? What is that portion of the lower division which is between 
the hip-bones called ? What is the name of the partition between 
chest and abdomen? Is there any partition between abdomen and 
pelvis ? What are the bony walls of the chest ? What are its princi- 
pal contents ? Why is not the abdomen as well walled as the thorax ? 

3. How many bones are there in the body ? In the spinal column ? 



34 THE HUMAN BODY. 

In the head? In the trunk? In the upper limbs? In the lower 
limbs ? 

Section II.— 1. What bones of the skull are movable? What 
organs of special sense are guarded by the bones of the skull ? 

2. What is the structure of a vertebra? W T hat is a process on a 
bone ? What canal do the vertebras make when they are joined ? 
With what cavity is this canal continuous? What springs are 
found in the spinal column ? W x hat is the position of the sacrum ? 
Of the coccyx ? 

3. What is the shape of a baby's spine? What are the natural 
curves of the back? Wliat curves are unnatural? What is the 
harm of a stoop? What are the causes of unnatural curves in 
the backbone ? 

4. How are the first seven ribs distinguished from the last five ? 
Which are called floating-ribs? What are the costal cartilages? 
What is their use ? What are the effects of compressing the chest 
and waist? 

5. Describe the sternum. 

6. W T here is the hyoid bone situated ? and what important organ 
is attached to it ? 

Section III. — 1. What are the divisions of the upper limb? 

2. What is the common name of the clavicle? What is its 
situation? 

3. What is the common name of the scapula? What is its 
situation ? 

4. Name the arm-bone. 

5. What are the bones of the fore-arm ? Which rolls over the 
other ? Which is most closely connected with the hand ? 

6. What are the divisions of the hand ? 

7. How many bones in the carpus ? 

8. How many bones in the metacarpus ? How many phalanges ? 
What in the human hand especially gives it an advantage over the 
hands and paws of lower animals ? 

Section IV. — 1. What are the divisions of the lower limbs? 

2, Why is the hip-bone called the os innominatum ? 

3. What is the longest bone in the body ? 



THE BONES AND JOINTS. 35 

4. Where is the patella situated ? 

5. Name the leg-bones. What is the shin? What is the use of 
the fibula? 

6. What are the divisions of the foot ? 

7. How many bones in the tarsus ? In the metatarsus ? How 
many phalanges? 

8. What is the effect of wearing too tight shoes ? Of having a 
high heel under the middle of the foot? What is the natural 
direction of the great toe ? What is the proper shape for a shoe ? 

Section V. — 1. Is a bone solid all through? What part is hol- 
low? What part is filled with thin-walled cells? What is contained 
in the cavity ? Why is it hollow ? Why are the ends of the long- 
bones enlarged? 

2. What is the structure of a short bone ? 

3. How do blood-vessels and nerves get into a bone ? What are 
the Haversian canals ? 

Section VI. — L What is the chemical composition of bone? 
How can the animal and mineral constituents be separated ? Why 
do the bones of old people break more easily than children's ? 

Section VII. — L What three kinds of joints are there in the 
body? 

2. Of the movable joints, what varieties are there ? 

3. What are the essential parts of a joint? How does a joint 
oil itself? 

4. Why are some people's joints looser than those of other 
people ? 

5. What is a sprain? 



THE FIGURE ON THE opposite page gives a general representation of 

THE MUSCULAR SYSTEM. 



40 THE HUMAN BODY. 



CHAPTER III. 
THE MUSCLES. 

Section I. — 1. The muscles are organs of motion. 
They cover the bones, and constitute the " flesh. " They 
are found also in the walls of the alimentary canal, and 
of the blood-vessels, and in other inward parts. The heart 
is chiefly muscle. 

2. The muscles with which we are most familiar, act 
when we will that they shall act. We can walk, run, or 
sit still ; we can move our arms or our heads as we will ; 
but we can not stop the beating of our hearts in this way. 
The movements of the intestines are also independent of 
our will. 

3. Muscles are accordingly divided into two classes, — 
voluntary, or those which are subject to the will; and 
involuntary, or those which are not subject to the will. 

4. The voluntary muscles constitute about two-fifths of 
the weight of the body. They are compactly arranged 
over the skeleton, most of them being attached to a bone 

Suggestions to Teacheks. — 1. A piece of fresh beef will illustrate to 
the naked eye the gross structure of voluntary muscle. With a micro- 
scope magnifying four hundred times, a small fragment teased out with 
a needle will show the structure of the fibers. The play of the muscles 
and tendons in the fore-arm is easily seen in a thin person. The action of 
involuntary muscle can be seen in the iris, w T hose muscular fibers contract 
under the influence of light, but are not subject to the will. 

2. Fibrous tissue is seen between the muscular bundles of beef. Ten- 
dons show in the leg of a fowl. 



THE MUSCLES. 



41 



at each end. They are of various shapes, according to 
their position and use. Some are long, some short: some 
are round, and some flat. In the living body, all the 
muscles of a limb are bound together 
and covered by fibrous tissue. 

5. Voluntary muscles are commonly 
attached to a bone, at one or both ends, 
by means of a tendon or aponeurosis. 
A tendon is a glistening cord of fibrous 
tissue. It is tough, and does not stretch. 
An aponeurosis differs from a tendon 
in being flat. If the muscle is flat, it 
ends in an aponeurosis : if it is round, 
it tapers down to a tendon. 

6. There are more than five hun- 
dred muscles in the body. Most of 
them are in pairs, the two sides of the 
body being alike. The smallest is the 
stapedius, a muscle in the ear, which 
is only one-sixth of an inch in length : 
the longest is the sartorius, which ex- 
tends from the hip to the leg below 
the knee, and is over eighteen inches 
in length. 

The biceps of the arm has two heads, 
both arising from the shoulder-blade, 
and is inserted into the radius just below the elbow. 
The great muscles which pass from the breast-bone to 
the upper end of the arm are called pectorals. The 
gastrocnemius constitutes a large part of the calf of the 
leg. Its tendon, called the tendon of Achilles, is inserted 
into the heel, and is the largest tendon in the body. 




42 



THE HUMAN BODY 



PROPERTIES OP MUSCLE. 

Section II. — 1. Muscle has a peculiar power of short- 
ening itself. There is a kind of elastic tissue in the body, 
of which a few ligaments are made, which, like rubber, 
will contract after it lias been stretched ; but muscle is 
the only tissue that contracts without being stretched 
first. When a muscle grows shorter, it grows thicker at 
the same time, just as the body of a worm will shorten 
and thicken. If, for example, I place my left hand on 
the biceps of my right arm, and then bend my elbow, I 
shall feel the biceps swelling, and growing hard : at the 




Fig. 24. 
1. Biceps Muscle. The dotted lines indicate the changed shape of the biceps when 
the fore-arm is drawn up. 



same time it has shortened, and thus drawn the bone 

to which it is attached up toward the shoulder. We do 

# not understand how it is that muscle contracts when we 

will that it shall. We can only say that it does so. 

2, Involuntary muscle has the same power of shorten- 



THE MUSCLES. 



43 



ing that voluntary muscle has. But it will not do this in 
obedience to the will. Cold contracts, and heat relaxes it. 
The involuntary muscle in the walls of the intestine con- 
tracts when food comes in contact with it. Many other 
influences produce the same effect, but the will which 
controls the voluntary muscle has no authority over the 
involuntary, Involuntary muscle never contracts as rap- 
idly as voluntary muscle sometimes does. It moves in a 
sluggish way. 



00 

w 
pq 



STRUCTURE OF MUSCLE. 

Section III. — 1. If we examine a little shred of vol 
untary muscle with a microscope which 

will magnify four liundr 

times, we shall see that the 

small fibers which are visi- 
ble to the naked eye ar 

made up of still smal 

fibers, and that these hav 

dark lines crossing them. 

These microscopic fibers are 
gathered into bundles, and these again 
into larger bundles. The muscle is 
made up of many such bundles, sur- 
rounded and bound together by fibrous 
membranes. We can readily see this 
in a piece of beef. The fibers con- 
stitute what we call the grain of the 
meat. 

2. Involuntary muscle, when ex- 
amined with a microscope, is also 
seen to consist of fibers. But they are much shorter than 




Fig. 26. 
Fibers of Involuntary 
Muscle. — 1. Fibereoaked iu 
acetic acid. 2. Nucleus. 



44 THE HUMAN BODY. 

the fibers of voluntary muscle; and they are broad in the 
middle, and taper to each end. They have no cross-stripes, 
and have a spot in the center called a nucleus. 

MUSCULAR EXERCISE. 

Section IV. — 1. It is a law of Nature, that every liv- 
ing thing, in order to remain in health, must do the thing 
that it was made to do. A stone was made to lie inactive 
and motionless. Men, as well as the lower animals, were 
made for activity and motion. Every part of the body 
must do the work that it was made to do. The muscles 
must move, the stomach must digest, the nerves must be 
in use, the brain must think. The part which is allowed 
to remain inactive becomes unhealthy and weak. This is 
the great law of exercise. 

2. This law applies especially to young persons. After 
the body has got its growth, and has become firm and 
strong, it can endure bad usage or neglect better than in 
the growing period. 

3. Some people are engaged in occupations which give 
abundant exercise to all the organs of body and mind. 
Such occupations tend to long life. Statistics kept in the 
State of Massachusetts for thirty years, of the length of 
life in different occupations, showed that the farmers lived 
the longest. 

4. Many employments require the use of the muscles 
more than of the brain. Persons engaged in such em- 
ployments should, during their hours of recreation, exer- 
cise their minds. 

5. Other occupations engage the mind while the body 
is inactive. Those who have such occupations should 
seek recreation in muscular exercise. 



THE MUSCLES. 45 



6. It is especially important that the muscles should be 
exercised, for several reasons. 

1. Because they are so large a part of the body. Nearly 
one-half the weight of a man is muscle. 

2. Because they are made capable of great activity. 
They are abundantly supplied with blood-vessels, and the 
current of blood should flow freely through them. When 
they are idle, its flow is sluggish. 

s. Because, when the muscles are exercised, all other 
parts of the body are refreshed. We may exercise the 
brain vigorously while the muscles are quite idle, and 
the blood circulates no faster. But, when we exercise the 
muscles, the heart beats more strongly, and the blood 
flows more rapidly, not only through the muscles, but 
also through the skin, the liver, the stomach, the brain. 
The organs which remove w r aste matters from the blood 
are more active, and the whole body is purified. Exercise 
is Nature's stimulant. 

7. Muscular exercise is valuable, not only because it 
promotes the general health, but also because it directly 
improves the muscular system. A strong and well-shaped 
body is to be desired. The ancient Greeks, who for their 
physical beauty and vigor, and their intellectual power, 
have been the admiration of all succeeding nations, made 
very much of the cultivation of the muscles. Their 
scholars and statesmen w T ere proud if they could win 
prizes in the great athletic games. Much of the work of 
life is done by the muscles. It will be better done if they 
are strong and w r ell trained. 

8. Three things are to be sought in the training of the 
muscles,. — l. Strength, 2. Alertness, 3. Endurance. 

l. Strength. The muscles increase in size and power by 



46 THE HUMAN BODY. 

use. It is important that this increase should be uniform. 
Exercises should be chosen with reference to the develop- 
ment of arms, legs, and trunk. It is a common mistake, 
to regard strength as the only end of muscular exercise. 
A man is not required to do the work of a horse. Great 
strength does not always imply good health. Athletes 
are sometimes overtrained, so that their health is impaired 
while their muscles are large. Prize-fighters frequently 
die early. 

2. Alertness. This is the power to obey quickly the 
commands of the will or the impulse of the senses. In 
many trades, and some professions, it is of the utmost 
value, Games which require keen watching and rapid 
movements develop it. 

s. Endurance. This is the power of continuing to make 
efforts for a long time without tiring out. It is not always 
the largest muscle that has the most of this quality. This, 
with healthy action of other organs, constitutes what is 
called " staying power," and gives the victory in a long 
race. It is acquired by regular exercise. 

9. Muscular exercises are valuable, also, because they 
commonly train the eye and the ear to quickness of 
perception. 

10. The muscles are larger and firmer in men than in 
women. Nevertheless, the need of muscular exercise is 
just as real for one sex as for the other. It is as truly 
requisite for their health and proper growth. Neither 
unsuitable dress, nor false ideas of propriety, should be 
allowed to deprive them of it. 

11. Exercise, to be most useful, should be regular. To 
take several hours of it to-day, and none to-morrow, is 
less beneficial than to take a moderate amount daily. It 



THE MUSCLES. 47 



should be taken, if possible, out of doors. Much of its 
benefit comes from breathing a great deal of pure air. 

The more heartily the mind is interested and engaged, 
the more the benefit. 

12. Violent exercise should not be taken directly after a 
full meal. At this time the stomach has work to do. If 
the blood is drawn away from it to the muscles, and all 
the strength is engaged in muscular efforts, the digestion 
will be checked. If such a practice be long continued, 
the stomach will be weakened. 

13. In muscular exercise, as in every thing else, it is 
important to avoid excess. It is excess to exercise so long 
or severely as to be unfitted for other occupations. It is 
excess to exercise until a muscle or limb is painfully ex- 
hausted, and does not soon rest. It is excess to attempt 
through ambition exercises that are beyond the strength. 
It is excess to engage in severe exercises when exhausted 
by mental or other labor. 

Excessive exercise sometimes results in bleeding from 
the lungs, sometimes in enlargement of the heart. That 
organ, being compelled to overwork, becomes too large; 
and this causes illness, and sometimes death. 

14. There are many small muscles in the face, which 
are attached by one end to the bone, by the other to the 
skin. By acting together, they give a great variety of 
expression. The thoughts and feelings are indicated. 
Grief causes one set of muscles to contract, joy another. 
So naturally is the action of particular muscles associated 
with certain emotions, that it is difficult for most people 
to conceal their feelings from one who is steadfastly ob- 
serving the countenance. The faces of the lower animals 
are not as well supplied with muscles, nor are they as soft 



48 TUE HUMAN BODY. 

and movable as the human face. They express only a 
limited number of thoughts and feelings. The face of 
the lion expresses dignity; that of the tiger, cruelty; that 
of the ox, patience. The expressions which are most fre- 
quently on the face become after a time permanent : thus 
the character is written on the countenance. A sullen or 
bitter temper makes an unpleasing aspect. A genial and 
kindly disposition will in time impart its own beauty to 
the face. 

EFFECT OF ALCOHOL ON THE MUSCLES. 

Spxtion V. — 1. By the action of alcohol, muscle is 
sometimes changed, in part, to fat. It thus becomes 
flabby and feeble. 

Alcohol affects the muscles indirectly, by affecting the 
digestion and the blood, and so spoiling their nourishment. 

The athlete training for a prize, knows well, that, if he 
indulges freely in alcoholic drinks, he will surely fail to 
bring his muscles to a hard and vigorous condition. 
Total abstinence from alcohol and tobacco are important 
for his success. 



QUESTIONS. 

Section I. — 1. What are muscles? Where are they found? 
2, 3, What two kinds of muscles are there? 

4. What holds the muscles together? 

5. What is a tendon? An aponeurosis? 

6. How many muscles in the body? Which is the longest? 
Which is the smallest? Where is the biceps humeri? Pectoral? 
Gastrocnemius ? Tendon of Achilles ? 

Section II. — 1 What is the special property of muscle? Can 
we explain the contraction of muscle? 



THE MUSCLES 49 



2. What is the difference between the contraction of voluntary 
and involuntary muscle ? 

Section III. — 1. How does voluntary muscle look under the 
microscope ? 

2. How does involuntary muscle look under the microscope? 

Section IV. — 1. What is the law of exercise? 

2. Is exercise more important for young than for older persons ? 

3. What class of people have the best prospect of long life ? 

4. 5. What kind of exercise is best suited to a muscle-worker? 
What kind to a brain-worker ? 

6. What three general reasons are there for muscular exercise? 

7. What special reasons ? 

8. What three qualities of muscle should be cultivated ? 
lL Name the conditions which make exercise useful. 

12. Name the cautions to be observed in exercise. 

13. What is excess in exercise? What are its results ? 

14. What is the use of the muscles of the face ? How is char- 
acter written on the countenance ? 

Section V. — 1. What change can alcohol make in muscle? 
How does it affect the muscles indirectly? What is the practice 
of athletes in training with regard to alcohol and tobacco? 



50 THE HUMAN BODY. 



CHAPTER IV. 
WORK AND WASTE.-THE BLOOD. 

Section I. — 1. The body, like not-living machines, 
tends to wear out by use. Even the enamel of the teeth, 
which is the hardest substance found in it, at length gives 
way. 

2. The soft parts wear out very rapidly. In every 
movement of a muscle, in every action of the brain, some 
of their particles are worn away. 

3. The body is always active. Even in sleep, the 
breathing muscles, and the heart, and the muscles of the 
digestive organs, are moving. The wear is, therefore, 
constant. 

4. But the body differs from a not-living machine in 
being able to repair itself. In early life, it does more than 
this. It builds itself up, and grow r s. When it has got its 
growth, it still repairs all waste, and may increase in 
strength and endurance for many years. At length there 
comes a period when it is not able to repair so much as it 
once could; it can not, therefore, endure so much wear, — 
the old can not be so active as the young; finally it is 
unable even to supply the waste caused by the simplest 
actions, such as breathing and digesting ; then life must 
cease. 

Suggestion to Teachers. — The least stain of blood, on a glass slide, 
under a microscope magnifying four hundred times, is sufficient to show 
the red globules. It is not always easy to find white ones. 



WORK AX J) WASTE. — THE BLOOD. 51 

5. Few people die of old age. Generally, before the 
time for such a death is reached, some disease attacks the 
enfeebled body, and overcomes it. 

6. The process of repair is going on all the time: but, 
during our waking-hours, waste is greater than repair; 
hence, every one must sleep several hours in each twenty- 
four. During sleep, the waste is very small; and the pro- 
cess of repair restores to the system each night what it has 
lost during the day. 

7. The need of sleep is indicated by a feeling of fatigue 
and drowsiness. These are the warnings that Nature 
gives us to stop for repairs. Without this feeling, we 
would not be willing to lie inactive for so much of each 
day. Since rest is very important, this feeling is made 
so strong that it is almost impossible to resist it. Ex- 
hausted men will fall asleep on horseback, or even 
walking. 

8. But Nature gives her warning in good time. If it is 
necessary to continue working for a while after we begin 
to feel tired, we can generally do so without injury; but 
we must rest afterward. However tired we may be at 
night, if we are rested by our night's sleep we are safe ; 
but if the wear of the day is not fully repaired, and we 
feel each morning more weary than on the morning be- 
fore, we are in danger. 

9. A very young infant sleeps most of the time. He 
requires less sleep as he grows older. Grown persons 
need from six to nine hours sleep every day. Indolent 
people often take too much. On the other hand, it is 
easy to injure the health, particularly in early life, by 
taking hours which belong to sleep for work or pleasure. 
This is especially injurious when the weary body and 



52 THE HUMAN BODY. 

mind are excited by stimulants, to make them forget the 
need of rest. 

10. Sleep, though the most perfect, is not the only, way 
of resting. When we have been using the muscles, we 
may rest them while using the brain. After study, hearty 
muscular exercise is rest. Entire change of occupation is 
rest. 

MATERIALS FOR REPAIR. 

Section II. — 1. The materials by which the waste of 
the system is repaired, are found in air, food, and water. 
Air must be taken in constantly, food and water at fre- 
quent intervals. We can live but a few minutes without 
air : without water we should perish in a few days. Men 
have lived without food for weeks, having air and water; 
but the body must at length be exhausted if these three 
things are not regularly supplied in sufficient quantity. 

2. We take oxygen from the air by the breathing 
apparatus. We take food and water by the digestive 
apparatus. Both are taken into the blood, and carried 
through the body, to be used as needed in every part. 

3. The blood not only carries the oxygen, food, and 
water to every part of the body : it also carries aw T ay 
from every part the ivaste matter wdiich is formed there, 
and delivers it to the organs which discharge it from the 
body. It has been likened to an express-agent, wdio goes 
about the streets of a city, leaving a parcel here, taking 
one there, — his wagon always loaded, though its contents 
are constantly changing. 

THE BLOOD. 

Section III. — 1, Blood is a reel fluid, not transparent, 
having a salty taste. It is a little heavier and thicker 



WOliK AND WASTE. — THE BLOOD. 



53 




Fig. 27. 

Red Corpuscles of Human 

Blood (400 Diameters). 



than water. If we look at a drop of it through a micro- 
scope, we shall see in it many small round bodies, shaped 
like a coin with a thick rim. These 
are only 30000 °f an m vh across, and 
are all of the same size. They are 
called red-blood corpuscles, or glob- 
ules. They make up nearly half the 
blood. 

2. Every animal that has a back- 
bone has red globules in its blood, 
but they differ in shape and size. 
In birds and reptiles they are not 
round, but oval, in shape, and have a spot in them called 
a nucleus. In all animals that have round globules, they 
are smaller in size than 

those of a man's blood, 
with two exceptions, the 
elephant and the sloth. 

3. We know by careful 
measurements the exact 
size of these globules in 
many animals. By ex- 
amining a drop of blood 
with a microscope, we can 
often tell what animal it 
came from. 

4. Such examinations are made of blood found on the 
clothing of persons accused of murder, and aid in deter- 
mining their guilt or innocence. But this evidence 
should not be accepted as decisive. There are possibili- 
ties of mistake. 

5. Besides the red corpuscles, there are also white cor- 




Fig. 28. 

Red Corpuscles of Frog's Blood (400 

Diameters j. 



54 THE HUMAN BODY. 

puscles, a little larger, and spherical in shape, in the pro- 
portion of one white one to three or four hundred red. 

6. The red globules have the property of attracting 
oxygen to themselves. They take it from the air in the 
lungs, and carry it to all parts of the body. 

7. These globules give the blood its red color. If they 
were all taken out, it would be transparent and color- 
less. When there is a plenty of red blood in the blood- 
vessels, there is a rosy hue in the cheeks, and the lips are 
cherrv red. This we call a healthy color. It is healthv 
because it indicates that there is blood enough, and that 
it is well supplied with globules. As these are the car- 
riers of oxygen, a good number of them means plenty 
of oxygen in the tissues; and that is necessary to good 
health. On the other hand, colorless lips and skin indi- 
cate a lack of red globules, scanty oxygen, and ill health. 

8. The watery part of the blood, in which the globules 
float, is called the plasma. This contains many sub- 
stances dissolved in it, some of which are derived from 
the food, and nourish the body; and some are waste mat- 
ters, which the blood is carrying away to be discharged. 

9. When blood flows out of the blood-vessels, it soon 
thickens into a jelly. This is called the coagulation of 
the blood. 

10. Blood does not coagulate in the blood-vessels during 
life if they are sound. If the blood is flowing very fast, 
it will not coagulate until the flow is checked. If the air 
is extremely cold, it does not coagulate quickly. 

11. It is this coagulation of the blood that saves us 
from bleeding to death when we are wounded. The clots 
which form, stop up the mouths of the cut vessels. 

12. In case of a ivound, the blood should be helped to 



WORK AND WASTE. — THE BLOOD. 55 

coagulate by pressing on the spot so as to check the flow. 
Sometimes it is necessary to tie a handkerchief or a string 
around the limb above, or sometimes below, the wound. 
In this case the bandage should not be kept on too long, 
as other parts of the limb may suffer from want of blood. 

13. Loss of blood causes great weakness, and at length 
fainting. When we faint, the heart almost stops its action, 
and the flow of blood becomes very slow. This gives it 
an opportunity to coagulate, and stop up the bleeding 
vessels. When the flow of blood can not be stopped, a 
fainting-fit may save life. 

14. The body of a man contains six or eight quarts of 
blood. The loss of more than half of his blood would 
be certainly fatal, and the loss of a very much smaller 
portion might be so. 

15. People near to death from loss of blood have some- 
times been restored by throwing into their veins blood 
drawn from another person. This is called transfusion. 
It is a delicate and dangerous operation, and not often 
useful. 

16. Some causes of impure blood are, — 
i. Bad; air. 

2. Lack of exercise. This makes the flow sluggish. The 
organs whose work it is to purify it become inactive. 
Waste matter accumulates. 

3. Too much or too rich food. The blood becomes loaded 
with matters which the system can not use and can not 
easily get rid of. 

4. Too little or too poor food. The blood becomes thin, 
and unequal to the nourishment of the body. 

5. Alcohol, which is itself an impurity, and unfits the 
blood for its work. 



56 TUB HUMAN BODY 



QUESTIONS. 

Section I. — 1. How does the body wear out? 

4, How is it kept in repair? Why must it finally die? 

6. Why do we need sleep ? 

7. Why is sleepiness a safeguard ? 

8. How can we know that we are not wearing out, when working 
very hard ? 

9. How much sleep does a grown person need ? 
10. Is sleep the only rest? 

Section II. — 1. From what materials is the waste of the body 
repaired? What is the most important? 

2, How do we take in oxygen? How do we take in food and 
water? How are these distributed through the body? 

3. What does the blood carry, besides the materials for repair ? 

Section III. — 1. What is blood? What are blood-globules? 
What is their size? What proportion of the blood do they make? 

2. What animals have red globules in their blood ? What is their 
shape in man's blood ? What is their shape in bird's blood. What 
animals have larger red globules in their blood than man? 

3, 4. How can we distinguish the blood of different animals ? 

5, What globules are there, besides the red ones? How numer- 
ous are they ? 

6, What do the red globules do? 

7, What makes the blood red ? Why do we say that rosy cheeks 
are a sign of health ? 

8, What is the plasma of the blood? What does it contain? 

9, What is the coagulation of the blood? 

10, Does blood coagulate in the blood-vessels during life ? What 
hinders coagulation ? 

Hi What is the use of coagulation ? 

12. How 7 should we treat a bleeding wound? 

13. How may a fainting-fit be of advantage to a wounded person? 

14. How much blood is there in the body? and how much may 
be lost without a fatal result? 

15. What is transfusion ? 

16. Mention causes of impure blood. 



The figure on the opposite page shows the heart and the great blood- 
vessels. 

The arteries are colored red, the veins are colored blue. 

The right auricle and right ventricle of the heart are seen, and the 
beginning of the pulmonary artery, coming from the right ventricle. 
Arching from the heart, and passing down the back, is the aorta (red). 
It divides, at its termination, into the two common iliac arteries. The 
carotid arteries pass up on the sides of the neck. The subclavian arteries 
pass off to the right and left, and are continued as the axillary arteries. 
The venae cavse, ascending and descending, lie by the side of the aorta. 
The internal jugular vein accompanies the carotid arteries. The external 
jugular is just outside of the internal. The other veins have the same 
names as the arteries which they accompany. The intercostal arteries 
and veins run along the edges of the ribs on each side. The kidneys are 
seen, one on each side of the aorta. 



GO THE HUMAN BODY. 



CHAPTER V. 
THE CIRCULATION. 

Section I. — 1. The blood is found in every part of the 
body. But the body does not hold it as a sponge holds 
water. It is rather like a house which has a supply of 
water carried through it in pipes. The blood in the body 
is all contained in pipes, called blood-vessels. 

2. It is constantly in motion. Starting from the heart, 
it moves through the blood-vessels off to distant parts of 
the body, and then back to the heart again, making a 
circle. The heart and blood-vessels are, therefore, called 
the organs of circulation. 

3. The blood-vessels are called arteries, capillaries, and 
veins. Coining out of the heart is a very large artery, 
called the aorta. This gives off branches as it passes on, 
and these branches,, again, other branches, growing smaller 
as they divide, until at length the smallest branches are 
called capillaries. 

4. The capillaries are very numerous, very small, and 
very close together. They form a net-work in every inch 
of bone and muscle and skin and brain, — a net-work 
finer than the finest silk. We can not put a fine needle- 
point into the skin without opening some of these capil- 

Suggestions to Teachers. — Section I. A beef's or sheep's heart, from 
the butcher's, will show all the parts named in the text. The action of the 
heart-muscle and of its valves may be partly illustrated with a Davidson's 
syringe. 



THE CIRCULATION. 61 

laries, and drawing blood, so close together they are. If 
we could take out from the body of a man all the flesh 
and bone, leaving the blood-vessels, there would still be 
sufficient to form a perfect figure. 

5. The arteries divide up into the capillaries, and the 
capillaries unite to form the veins. The little veins thus 
formed, unite to form larger veins, and so on, until at last 
they are all gathered into two large veins which enter the 
heart. These are called the vena cava superior, and the 
vena cava inferior. 

6. The walls of the capillaries are very thin. Although 
there are no openings in them, a portion of the blood 
soaks through into the surrounding tissues; and, on the 
other hand, fluids containing waste matter soak into them, 
to be carried away. 

THE HEART. 

Section II. — 1. The heart is made of muscle, and is 
hollow. It is the pump which keeps the blood moving. 

2. It is situated in the chest, resting on the diaphragm, 
chiefly on the left side of the middle line. It is shaped 
like a pear, with the small end pointing down, and to the 
left. 

3. It is inclosed in a sac called the pericardium. This 
sac is also pear-shaped ; but the large end is on the dia- 
phragm, and the small end points up. 

4. The pericardium is lined with a very smooth mem- 
brane. The heart is covered with a continuation of the 
same membrane. This membrane is kept glossy and 
moist by a fluid that it gives out. When the heart moves 
in its sac, these two smooth membranes rub together with- 
out friction. 



62 



THE HUMAN BODY. 



5. The apex j or point, of the heart is just beneath the 
fifth rib. Its base is a little to the right of the breast- 
bone. It extends up as high as the third rib. It is held 
in place by the diaphragm beneath it, and the large blood- 
vessels which run into and out of it. It is about as large 
as the fist, weighing from eight to twelve ounces. 

6. We find, on examining the interior, that it is divided 
into four cavities. There is a division which runs across, 



Pulmonary artery 
Vena cava superior. % 



Pulmonary veins. *?'!..., 

Right auricle. . — 
Tricuspid valve. 
Vena cava inferior. •— — - t 



Aorta. 



Pulmonary artery. 
/ 




-/Pulmonary veins. 



■•• Left auricle. 
« Mitral valve. 



""**«« Left ventricle. 



Right ventricle, s' 



Aorta. 

Fig. 29. 
Representation oe a Section of the Heart (Diagrammatic). 



and one which runs lengthwise. This last divides it into 
right and left sides, the other into auricles (Latin, auricula, 
the external ear) and ventricles (Latin, ventriculus, the 
belly). These cavities are of nearly the same size, each 
holding about two ounces. The walls of the auricles are 
thin and loose. The wall of the right ventricle is about 
a sixth of an inch thick. That of the left ventricle is 
half an inch thick. 

7. The two large veins which bring the blood from the 



THE CIRCULATION. 



63 



body back to the heart, open into the right auricle. Be- 
tween the right auricle and the right ventricle, there is 
an opening about an inch in diameter. This opening is 
closed by the tricuspid (three-pointed) valve. This con- 
sists of three thin flaps, whose edges meet when the valve 
is shut. This valve opens from the auricle, and shuts so as 
to prevent the blood from passing back from the ventricle 
to the auricle. There are fine cords attached to the edges 
of these flaps, and to the wall of the cavity below, to pre- 
vent their shutting back too far. 

8. Opening out of the right ventricle is the pulmonary 
artery. This soon divides into tw T o, one of which goes to 
the right, the other to the left, lung. They there divide 
into capillaries, and 

the capillaries pass 
into the pulmonary 
veins. These are 
two in number for 
each lung. They 
empty into the left 
auricle. 

9. At the begin- 
ning of the pulmo- 
nary artery is a set of valves which prevent the blood 
from flowing back into the heart. These valves, called 
semilunar valves, are three pockets hung on the wall of 
the artery, their edges meeting all around. They open 
away from the heart; and, when the blood is going in 
that direction, they flatten up against the wall, just as a 
pair of doors will when a crowd is pushing through them. 
When the blood sets back toward the heart, it fills the 
pockets; and they bulge out, and together fill the tube, 




Fig. 30. 
Semilunar Valves open. 



64 



THE HUMAN BODY. 




and stop it up. These are very perfect valves. They are 
flexible, and float open like thin veils when the blood 
wishes to pass in the right direction ; but they are strong ; 
and, the harder it presses back, the tighter they fit. 
10. The left auricle is similar to the right. The opening 
between it and the left ventricle is an 
inch in diameter, and is closed by the 
mitral valve. 

The mitral valve differs from the tri- 
cuspid in having two flaps instead of 
three. When closed, it resembles a 
miter, or bishop's cap. 

11. The left ventricle differs from the 
right only in having thicker walls. 

12. Out of the left ventricle opens 
the great artery of the body, the aorta. 

Its entrance is guarded by semilunar valves precisely like 
those of the pulmonary artery described above. It gives 
off numerous branches, which go to all parts of the body, 
finally dividing into capillaries. From these capillaries 
the blood is returned by the veins to the right auricle. 

13. The muscle of which the heart is composed is pe- 
culiar. It is striped, and yet not voluntary. As it must 
act during sleep, it is made independent of will or thought. 

The heart and the blood-vessels are lined by a mem- 
brane as smooth as satin. 



Fig. 31. 

Semilunar Valves 
partly closed. 



ACTION OP THE HEART. 



Section III. — 1. The heart is, in the body, what the 
mainspring is, in a watch. Like all other muscle, it has 
the power of contracting. By constant and regular con- 
tractions it keeps up the circulation, and thus sustains life. 



THE CIRCULATION. 65 

2. The heart-muscle is remarkable for its endurance. 
No other muscle could do its work. Through a whole 
lifetime, sometimes a hundred years, it never pauses for 
one minute. 

3. It might seem, therefore, to be an exception to the 
general law, that rest is necessary for all organs; but, after 
each contraction, it has a very short time of relaxation and 
rest. This time is not more than two-fifths of a second; 
but, as it comes every second, its whole amount in twenty- 
four hours would be eight or nine hours. Moreover, in 
sleep the heart beats less rapidly, and is not obliged to 
make the special efforts which are so often required of it 
during the day by rapid movements or excitement. 

4. The heart is, doubtless, tired after labor, and con- 
tributes to the general sense of fatigue; but in health we 
have no special feeling of the heart. Great and long-con- 
tinued care such as business men are often subjected to, 
or protracted muscular exertion like that of soldiers on a 
march, sometimes so exhausts the heart, that it acts irreg- 
ularly, and feels distress. This condition, known to 
physicians as "irritable heart," maybe brought on by 
prolonged dissipation. 

5. The number of heart-beats in a minute varies at dif- 
ferent periods of life. In an infant it is one hundred and 
twenty or more; in a child under fourteen, eighty or 
more; in a grown person, about seventy-two. But it may 
be ten beats more or less; and, in rare cases, there is a still 
wider variation in health. 

6. Many things cause a temporary variation. It is less 
in sleep: it is greater in active exercise. One reason why 
we soon become exhausted by running, is that the heart 
is stimulated to such rapid action. It is greater after eat- 



66 



THE HUMAN BODY. 



ing in moderation. Excitement of any kind increases the 
number and force of heart-beats so that they can be felt, 
and sometimes heard. In the affection called palpitation, 
the action of the heart is unnaturally rapid, and some- 
times hard enough to shake the body. 

7. The heart has been called a pump. It is really 
a double pump. There are two streams flowing out of 
it with each contraction, and two streams flowing into it 
with each relaxation. The two sides 
of the heart have no direct communi- 
cation, and are often spoken of as the 
right and left heart, as if they w r ere 
separate. 

8. There are, accordingly, two dis- 
tinct circles of blood. One begins at 
the right ventricle, goes through the 
pulmonary artery to the lungs, and 
back through the pulmonary veins to 
the left auricle. This is called the 
pulmonary circulation, or the lesser 
circulation. 

The other begins at the left ventricle, 
and goes through the aorta, to be dis- 
tributed to all parts of the body, and, 
passing through the capillaries and 
veins, is poured into the right auricle by the vena cava 
superior and the vena cava inferior. This is called the 
systemic or greater circulation. 

9. Let us observe a contraction and its effect. Suppose 
the auricles to be full. The blood has been pouring 
into the right one from the veiise cavse, and into the left 
from the pulmonary veins. Now the auricles contract. 




Fig. 32. 

Representation of the 

Greater and Lesser 

Circulation. 



THE CIRCULATION. 67 

Their contents can not go back into the veins, for they 
are full ; but the ventricles have just emptied them- 
selves, and are opening for a new supply. The blood is 
therefore forced suddenly on through the passages, with 
their open valves, into the ventricles. Directly the ven- 
tricles, now full, begin to contract. The blood sets back 
against the valves it has passed, and shuts them tight, 
just as a crowd trying to get through a door which 
opens towards them will often close it: but the passages 
into the pulmonary artery and the aorta are clear, — 
their valves (the semilunar) open out ; into them the 
blood pours, the ventricles still contracting until all is 
squeezed out. Then the blood in the arteries sets back, 
and shuts the semilunar valves; and the ventricles re- 
lax, and open for another supply. 

SOUNDS OP THE HEART. 

Section IV. — 1, If the ear be placed upon the chest 
over the heart, two sounds can be distinctly heard, re- 
peated with each beat. One is quickly followed by the 
other, and then there is an interval. The second is 
shorter, and higher pitched than the first. They may be 

— i fc- 



indicated by the signs zu* ^~ The first sound is 

lub - dub. 

caused chiefly by the closing of the tricuspid and mitral 
valves, as the ventricles contract. The second sound is 
caused by the closing of the semilunar valves after the 
blood has passed into the pulmonary artery and aorta. 
When the heart is diseased, these sounds are changed ; 
and the changes in sound indicate to the ear of the 
physician the particular changes in the heart. 



68 



THE HUMAN BODY. 



Temporal. 



Carotid 



Aorta 




Subclavian. 

Axillary. 
Brachial. 



.— Kadial. 



Anterior tibial 



Fig. 33. 
Representation of the Arteries. 

THE ARTERIES, VEINS, AND CAPILLARIES. 

Section V. — 1. The aorta arches from the base of 
the heart across to the backbone, by the side of which 



THE CIRCULATION. 69 

it descends. On a level with the top of the hip-bones, it 
divides into two vessels, one of which supplies each of the 
lower limbs. From the arch, branches are given off, 
which supply the head and the arms. 

2. In the thigh, the large vessel which carries the main 
stream is called the femoral artery. In the leg it is called 
the tibial artery. 

3. The carotid arteries carry the blood from the arch to 
the head. They pass up on each side of the neck, and 
their throbbing can often be seen. The subclavian ar- 
teries lie behind the collar-bones. They extend to the 
armpit, and in that situation receive the name axillary. 
From the armpit to the elbow they are called brachial. 
At the elbow they divide into the radial and ulnar. The 
radial lies on the thumb-side of the fore-arm, and is the 
one in w T hich the pulse is commonly felt. 

4. All the large arteries lie deep. They can be felt or 
seen on the surface, only in a few places. But many large 
veins lie just beneath the skin, and can be traced for some 
distance. 

The deep veins run by the side of the arteries. 

5. The veins frequently have the same names as the 
arteries which they accompany. Sometimes they have 
special names. The large veins of the neck are called 
jugular veins. The superficial jugular is the prominent 
vein just beneath the skin on each side. 

6. The blood flows in the large arteries much more 
rapidly than in the small ones. Its flow is slower in the 
veins than in the arteries. It is slowest of all in the 
capillaries. This is for the same reason for which a 
stream flows more slowly when its channel is wide than 
when it is narrow. The capillaries are very small; but 



70 



THE HUMAN BODY. 




there are so many of them, that their total blood-channel 
is reallv wider. It is estimated that it is three hundred 
times as wide as the aorta. 

7. Though many men of great minds gave much study 
to the human body, it was not learned until less than 
three hundred years ago that the blood circulated. Wil- 
liam Harvey, an English physician, made the discovery, 

and gave it to the world. 

8. The walls of the capillaries 
are a single layer of a thin mem- 
brane. Through them nutritious 
fluids soak out, and waste fluids 
soak in. 

9. Some points in which ar- 
teries and veins differ : — 

1. In the direction of their cur- 
rent. In arteries it always runs from the heart: in veins 
it always runs toward the heart. 

& In position. We do not find 
large arteries running just beneath 
the skin, as veins do. 

3. In color. The blue tint of their 
blood shows through the walls of 
the veins. 

£ In thickness. The arterial walls 
are thicker and firmer. 

5. The veins have valves at inter- 
vals in their course, which allow the 
blood to move forward, but not 



Fig. 34. 
Capillary Plexus magnified. 




move 
backward. 

10. In case of a wound, we can 
tell whether the blood is from an artery or a vein — 



Fig. 35. 

Vein laid open, showing 

the Valves. 



THE ClllCULATlON. 71 

1. By its color. Venous blood is dark : arterial blood is 
light. 

2. By the manner of its floiv. Venous blood flows in a 
steady stream, arterial blood in jets. 

11. The flow of blood from a vein stops more readily 
than that from an artery. A bandage is commonly suf- 
ficient. The arterial flow is more forcible. When the 
blood spurts, it must be checked by firm pressure on the 
vessel until a physician arrives. It may be necessary to 
tie the artery. 

The pulmonary artery is peculiar because it carries 
blue venous blood. The pulmonary veins carry red ar- 
terial blood. In these respects they are exceptions to the 
general rule. 

12. Arteries and veins are very strong. In experiments 
made, they have borne a pressure equal to a weight of a 
hundred pounds without bursting. But they sometimes 
burst. In old age they become brittle. Certain diseases 
make them brittle. 

THE PULSE. 

Section VI. — 1. At a certain spot in the wrist, we can 
feel a regular beat, which we call the pulse. A pulse may 
be felt in several other places/but the wrist is the most 
convenient. The pulse is a sudden rising-up of the wall 
of the artery under the finger, and a slight stirring of the 
wdiole artery in its bed. 

2. Every time the heart contracts, four or five ounces 
of blood are thrown into the arteries. These, being elastic, 
stretch to receive it. Between the beats they contract, 
forcing the blood along into the capillaries. 

This stretching is greatest in the aorta, close by the 



72 THE HUMAN BODY. 

heart, and diminishes as the vessels grow smaller. By 
the time the capillaries are reached, there is no stretching, 
hence no pulse. The veins have no pulse. 

3. The pulse tells us, — 

L Hoiv fast the heart is beating. 

2. Hoiv strong its beat is. 

3. Hoiv firm the coats of the arteries are. The last fact 
is important. The arterial walls are sometimes flabby, 
and sometimes hard and resisting. Their condition indi- 
cates the state of the system. 

VARIATIONS IN BLOOD-SUPPLY. 

Section VII. — 1. You might suppose, from what has 
been said of the circulatory apparatus, that the same 
blood-vessels are always of the same size, and that the 
blood-supply to the same part is at all times of the same 
amount. This is not the case. Although there are no 
stopcocks in the blood-vessels, there is a contrivance of 
Nature by which the size of the blood-vessels and the 
amount of blood in any part is increased or diminished 
according to the need of the moment. 

2. In this way the blood is partly shut off from the 
brain when we need sleep ; it is turned on to the stomach 
during digestion, and to the muscles in active exercise; it 
is shut off from the skin when it is cold, and sent there 
to be cooled when we are warm. 

3. The walls of the arteries consist partly of fibers of 
involuntary muscle running crosswise. When these mus- 
cle-fibers contract, they make the artery smaller: when 
they are relaxed, it is larger. They are not under the 
control of the will, but are influenced by special causes. 
For example, the arteries in the coats of the stomach will 



THE CIRCULATION. 



grow "larger when food touches it. The arteries of the 
salivary glands will grow larger, and fill with blood for 
the manufacture of saliva, when we smell food, thus " mak- 
ing the mouth water." The arteries of the skin will grow 
larger, and fill with red blood, wdien exposed to heat. The 
arteries of the face will expand, and cause a blush, when 
Ave feel shame. 

4. The apparatus which regulates the size of the arte- 
ries belongs to the nervous system. 

EFFECT OF ALCOHOL ON THE CIRCULATION. 

Section VIII. — 1. Alcohol in moderate amount makes 
the heart beat faster. In health it beats fast enough; 
and the extra beats, which amount to a good many in a 
day, are labor lost. Worse than this, they are wearing 
out that patient organ. 

2. Alcohol has the power to change muscle gradually 
into fat. The heart is particularly liable to this change. 
As the fibers soften down, it loses its strength. It can 
not do the work of pumping the blood through the body 
w T ith its natural vigor. The body, therefore, suffers in 
every part. Such a fatty, soft heart is liable to break 
suddenly. 

3. As old age comes on, the walls of the arteries fre- 
quently become changed in previously healthy persons. 
They get fatty and soft, or chalky and brittle, in spots. 
In this state they easily burst, if by excitement, or over- 
eating, or some other cause, they are unusually full. This 
is especially liable to occur in the blood-vessels of the 
head. The blood pours out; and, as the skull is a tight 
box, the brain is pressed so hard that it can not act. 
The person so affected becomes unconscious, and is very 



7 4 THE II UMAX BODY. 



likely to die. This takes place suddenly, and it is called 
apoplexy. 

4. Apoplexy is a disease of advanced life. These 
changes do not take place in the arteries of the young 
without special causes. Alcohol is such a cause. It 
makes the young man old before his time, and liable to 
sudden death by the rupture of an artery in the brain. 



QUESTIONS. 

Section I. — 1. In what way is the blood held in the body? 

2. Why are the heart and blood-vessels called organs of circula- 
tion? 

3. What are the three kinds of blood-vessels ? 

4. Describe the capillaries. 

Section II. — 1. What is the heart? 

2. Where is it situated? 

3. What is the pericardium? 

4. How is friction from the movements of the heart avoided? 

5. Where is the apex of the heart? How high does it extend? 
How is it held in place? How large is it? 

6. How is its interior divided? Name its cavities. What is the 
size of each? What is the thickness of their walls? 

7. Describe the passage between the right auricle and ventricle, 
and its valve. What vessels open into the right auricle? 

8. What vessel opens out of the right ventricle? What is its 
course? What vessels empty into the left auricle? 

9. Describe the semilunar valves of the pulmonary artery. 

10. Describe the passage between the left auricle and ventricle, 
and its valve. 

11. What is the difference between the left and the right 
ventricle? 

12- Describe the aorta and its valves. 
13. Describe the muscle of the heart. 



THE CIRCULATION. 



Section III. — 1. What does the heart do? 

2. Does the heart get tired? 

3. How does the heart rest? 

4. How many times does the heart beat in a minute? 

5. What causes make the number of beats in a minute greater 
or less ? 

6. Why may the heart be called a double pump? 

7. What is the lesser circulation? What is the greater circula- 
tion? 

8. Describe in full a contraction of the heart. 

Section IV. — 1. What sounds does the heart make, and how? 

Section V. — 1. Describe the course and termination of the 
aorta. 

2. Where is the femoral artery ? the tibial ? 

3. Where are the carotids, the subclavian arteries, the axillary, 
the brachial, the radial, the ulnar? 

4. Do large arteries run as near the surface as large veins ? 

5. How are the veins named? Where are the jugular veins? 

6. Where does the blood flow fastest? Where slowest? 

7. Who discovered and proved the circulation of the blood? 

8. What are the walls of the capillaries? 

9. Name some points in which arteries and veins differ. 

10. How can we tell, in case of a wound, whether the blood comes 
from an artery, or from a vein? 

11. Is the flow from a vein as easily stopped as that from an 
artery ? 

12. Are veins and arteries strong? 

Section VI. — 1. What is the pulse? 

2. Is there any pulse in the capillaries? in the veins? How does 
the blood flow from an artery? How from a vein? How from the 
capillaries? 

3. What does the pulse tell us? 

Section VII. — 1. Is the supply of blood to the same part always 
the same? 

2, 3, 4. How is it made greater or less? 



76 THE HUMAN BODY. 

Section VIII. — 1. What is the immediate effect of alcohol on 
the heart? 

2, What change does alcohol sometimes cause in the substance 
of the heart? 

3, What change does alcohol sometimes cause in the blood- 
vessels ? What is apoplexy ? 

4, How does alcohol cause it? 



FOOD AND WATER, STIMULANTS, ETC. 



77 



CHAPTER VI. 

FOOD AND WATER, STIMULANTS AND 
NARCOTICS. 

Section I. — 1. By food we mean all substances that 
we eat or drink to satisfy hunger and nourish the body. 

2. If we have to repair any manufactured article, we 
use the same kinds of material that the article was made 
of. We repair a harness with leather, a stove with iron, 
a table with wood. So our food, which repairs the body, 
must contain the same substances that the body contains. 

3. Analysis by the chemist shows that the body of man 
consists of fifteen substances, called elements. 1 



Elements. Parts in 100. 

Oxygen 72. 

Hydrogen 9.1 

Nitrogen 2.5 

Chlorine 085 

Fluorine 08 

Carbon 13.5 

Phosphorus 1.15 

Calcium 1.3 



Elements. Parts in 100. 

Sulphur 1476 

Sodium 1 

Potassium 026 

Iron 01 

Magnesium 0012 

Silicon 0002 

Manganese A trace. 



4. Our food must' contain every one of the above ele- 
ments. Of some, the body contains little; and we require 



1 These substances are not always in exactly the proportions given in 
the table. Each would differ in amount in different bodies, and in the 
same bodv at different times. 



78 THE HUMAN BODY. 

but little in our food. Sulphur is one of these. Others 
are abundant in the body, and are found in almost every 
article of food. Carbon is one of these. If any of these 
elements is entirely wanting in our food, we suffer, and 
would starve to death for lack of some of them. If we 
should try to live on food which contained no phosphorus, 
for example; we should become diseased, and die. Almost 
every thing that we eat contains phosphorus. 

5. Other elements than the fifteen given above, are not 
required in our food. Silver, for example, does not form 
part of the body, or of our food , but nitrate of silver is 
sometimes used as a medicine. 

6. All of these fifteen elements are found in the air, the 
earth, and the water. But animals can not feed on earth 
and air and water. Plants can, and that is one of the 
great distinctions between plants and animals. Four- 
fifths of the air is nitrogen. But men, and other animals, 
would die for want of nitrogen, even while they were 
drawing it into their lungs with every breath, if they 
could not get food, containing it. 

7. It is the ivork of plants to take the elements, and make 
them into food for animals. The plant feeds on earth, 
air, and water. This earth, air, and water become a part 
of itself. The animal feeds on the plant, or on other 
animals. 

8. Probably every plant is food for some animal. But 
there are very many which are not food for man. Some 
are poisonous. A large number contain the necessary 
elements, but can not be digested by the human organs of 
digestion. A fertile prairie which would fatten a herd of 
buffaloes would starve a man; because the grasses, though 
not poisonous or distasteful, contain too much indigest- 
ible matter for his stomach. 



FOOD AND WATER, STIMULANTS, ETC. 79 

9. Some animals live only on other animals. Theit 
teeth are not fit for chewing vegetable food Other 
animals live wholly on plants. Their teeth are made for 
grinding, but not for tearing flesh. The cow, for example, 
has no cutting-teeth in her upper jaw. She has broad 
grinders. Man eats both animal and vegetable food. 
His teeth are adapted to both. 

10. The infant, and the young of many of the lower 
animals, live on milk. No other article of food so well 
combines all the necessary elements as this. It is easily 
digested, and, after infancy is passed, is still an excellent 
article of diet. In sickness it is often used with advantage 
as the sole nutriment. 

11. Man's ordinary diet consists of meats (including fish 
and eggs), starchy foods, sugar, and fat. 

MEATS. 

12. Of meats, there are many kinds. The appetite is 
gratified, and the body better nourished, by a variety. 
Beef is the best. Pork is the staple meat-food of large 
numbers of people It is not so wholesome as beef, for 
two reasons : — 

1. It commonly contains a great deal of fat, — too much 
for constant use. 

2. It is more likely than beef or mutton to contain the 
young of the tapeworm, and other parasites. 

Veal is tender and good, but not so easily digested as 
beef, nor is it so nourishing. Lamb is very easily digested. 
Mutton is more nourishing than either lamb or veal, and 
is nearly as good food as beef. To some stomachs, how- 
ever, it is not acceptable. Each of the various kinds of 
game has its peculiar flavor, but they do not differ much 
in nutritive value. 



80 THE HUMAN BODY. 

All meat is better and more tender for being kept for a 
time after killing. 

13. Fish, on the other hand, is better when perfectly 
fresh. It does not differ very much from flesh in its 
chemical composition; though it contains more water, and 
less fat. It is lighter and less stimulating than flesh. 

14. Of shell-fish, oysters occupy the first place. They 
are palatable, light, and nourishing. They tempt the 
appetite of an invalid without distressing his stomach. 
In spring and early summer, they should not be eaten. 

15. Lobsters, crabs, and shrimps are less digestible. 
Vinegar and stimulating spices are commonly added to 
them, which spur up the stomach to its task. They should 
be avoided by invalids. 

16. Eggs contain much nourishment, solidly packed 
away for the support of the young fowl before he breaks 
out of his shell. They are palatable, and easily digested. 

STARCHY POODS. 

17. The starchy foods include all the grains — wheat, 
oats, corn, etc. — and vegetables. 

Dried ivheat contains, in 100 parts, 66 parts of starch. 

Dried oats contain, in 100 parts, 60 parts of starch. 

Dried rice contains, in 100 parts, 88 parts of starch. 

When we remember that many millions of the human 
family live chiefly on rice, whose solid substance is almost 
all starch, we have good proof of the importance of starchy 
food. 

18. Besides starch, the grains contain mineral matters, 
fat, sugar, and a substance, similar in chemical composition 
to meat, called gluten. 

Wheat is, on the whole, the most valuable of the grains 



FOOD AND WATER, STIMULANTS, ETC. 81 

as food; and men prefer it when they can get it. But each 
grain has its own advantages. Corn is rich in oil. Oats 
have much mineral matter, and much fibrous, branny 
substance, which make them indigestible for some delicate 
stomachs. For the majority they are healthful. It has 
been claimed that ground wheat is better food with the 
bran in it, — in which condition it is called graham flour, 
— than when the bran has been separated from it, and it 
has been made into fine flour. In sifting out the bran, we 
take away a good deal of nutritive substance ; and what is 
left is chiefly the starch. The advocates of this view were 
numerous a few years ago, and were called Grahamites, after 
their leader Graham. Nevertheless, fine white flour is still 
the choice of the majority. It is true that much nourish- 
ment is lost in the bran. But it is so mingled with woody 
matters, that it is not easily extracted by the stomach. 
For healthy people, it is better to use white flour, and 
to get, in other and more digestible foods, what is con- 
tained in the bran. But a stomach that is sluggish in its 
action, is stimulated and aided by the presence of the bran. 
For such, graham flour is excellent food. 

19. The potato is the most popular of all vegetables, 
though it has not been in common use more than three 
hundred years. It has been estimated that it forms at 
least three-fifths of the food consumed in Ireland. 'Its 
chief solid ingredient is starch. Much of the starch used 
in the laundry is extracted from potatoes. It is superior 
to other vegetables in being drier, and containing less 
fibrous substance. 

20. Pease and beans contain very little water, and a 
great deal of solid matter. They are very nutritious, and 
are most valuable for feeding armies, and other lars;e 



82 



THE HUMAN BODY. 



bodies of men, because they contain so much in small 
bulk. But, because they are so solid, it is hard for the 
stomach to digest them. 

21. Turnips, beets, cabbages, and other garden vegetables, 
contain more water and less nutritive matter than those 
already referred to. They form an agreeable and health- 
ful addition to more nutritious articles. 






SUGAR. 

22. There are many kinds of sugar, all sweet, but 
differing in taste and solubility. Most of our vegetable 
food contains sugar, and a great deal of pure sugar is used 
in addition to this. It is especially pleasing to the taste. 
The fact that children are so fond of it, is a proof that it 
has important uses in the growing period. But, if too 

much is eaten, it spoils 
the appetite and diges- 
tion, and injures the 
health. 



FAT. 

23. Most vegetable, as 
well as animal, foods con- 
tain some fat. It is cus- 
tomary to add oils, or 
fats of some kind, to other 
food. It is itself nutri- 
tious, and aids in the 
digestion of other things. 
Butter is the oil of milk. 
If we look at a drop of milk with a microscope, we see in- 
numerable little particles of oil. Oil is lighter than water; 




o 

oo Q o 

oo r 

Fig. 36. 

A Drop of Milk magnified, showing the 

Oil-globules. 



FOOD AND WATER, STIMULANTS, ETC. 83 

and, therefore, if milk is allowed to stand, the oil will rise 
to the surface, making the cream. After the cream is 
taken off, the milk looks thinner and more transparent. 
If all the cream could be removed from it, it would be 
clear, like water. In making butter, the milk is churned 
until all the oily particles are stuck together in a mass, 
and the watery part is separated: this latter is called 
buttermilk. 

COOKING. 

24. Animals eat their food raw. Men, even the most un- 
civilized, cook much of it. Cooking is useful in three ways. 

1. It renders food more digestible. 

2. It kills parasites in meats, and stops putrefaction. 

s. It creates flavors which are attractive, and stimulating 
to the digestion. 

25. Raw meat is not unpalatable: a fondness for it is 
often acquired. A disease called trichinosis is caused by 
eating pork, wdiich contains a minute worm called a trich- 
ina. This worm can not be recognized in pork without 
a microscope. It is killed by cooking: smoking is not 
sufficient. The disease is, therefore, found only among 
those who have eaten raw pork. Tape-worms are also 
acquired by eating raw pork and beef. 

26. We can not digest starchy foods, such as the grains 
and vegetables, in sufficient quantity, unless we cook them. 
By cooking, we soften them so that they can be easily 
separated into fragments, and dissolved by the digestive 
juices. Besides, we add to them, in cooking, various 
articles, such as salt, fat, sugar, and spices, which improve 
their taste. Flour is, in this way, made into bread, and 
cake, and pastry of many kinds. 



84 THE HUMAN BODY. 

27. The essential points for making good bread are, — 
/- Good flour. 

2. Thorough kneading, to mix all the ingredients. 
s. Good yeast. 

4. Good judgment exercised in keeping the rising mass 
just warm enough, and letting it rise just long enough. 

5. Having the oven just hot enough, and taking out the 
bread at just the right time. 

28. Good bread is light and sweet. Bread is light when 
the carbonic-acid gas formed in the fermentation caused 
by the yeast has penetrated the whole loaf, making in- 
numerable holes and pores in it. When such bread is 
eaten, the digestive juices easily enter these pores, and 
spread through and act upon every part. 

Bread is heavy when carbonic-acid gas has not pene- 
trated the mass, either because the yeast is poor, or the 
flour is poor, or because it has not been thoroughly 
kneaded. It makes a solid lump in the stomach, which 
the digestive juices can not easily enter; and that organ 
becomes weary and sore in struggling with it. 

Bread may be sour, either because there is too much 
yeast in it, or because fermentation has gone on too long. 
In that case, acetic acid is formed in it. 

29. Pastry and cake are not so wholesome as bread. 
They please the taste, and in small amounts are not 
injurious. Pie-crust is not commonly so light as bread. 
Besides, it has a good deal of lard or butter thoroughly 
mixed with it. This fatty matter, which is not acted upon 
by the juices of the stomach, coats over the particles of the 
flour, and prevents the gastric juices from reaching them; 
so they must pass out into the small intestine undigested. 
This is the reason why all food fried in fat is less easily 



FOOD AND WATER, STIMULANTS, ETC. 85 

digested than food cooked in other ways. In the process 
of frying, the fat is so thoroughly mixed with the food, that 
it renders it partly proof against the stomach-juices. 

Cake contains too much sugar and butter, in proportion 
to its other nutritive matters, to be wholesome in large 
quantities. 

30. Cookery is an art which is very important to health 
and comfort. It must be learned by practice. But those 
who understand the principles of chemistry and physi- 
ology, on which it rests, will acquire it more readily, and 
be more completely masters of it. 

MINERAL SUBSTANCES. 

31. Mineral substances are mingled with all our food. 
Salt is the only solid mineral matter that we take pure. 
It enters into every part of the body, solid or fluid, and 
aids the processes of life. 

Mineral matters are not commonly changed by digestion. 

WATER. 

32. Water forms about seventy of every hundred parts 
in the body. It must be constantly supplied, therefore, to 
make up for the waste of the parts. Digestion, absorp- 
tion, and circulation would stop without water. The 
craving for it is stronger than for food. 

33. Waters used for drinking always contain a small 
portion of mineral salts, of gases, and of vegetable mat- 
ter. Water which is absolutely pure — as only distilled 
water is — is flat and tasteless. The mineral matters in 
drinking-waters are such as are not harmful to the sys- 
tem, unless there is too much of them. In that case, they 
are irritating to the bowels and kidneys. When water is 



8G THE HUMAN BODY, 



carried through lead pipes, it sometimes dissolves enough 
of the lead to become poisonous. Whether it will do this, 
or not, depends on what it already contains. Some 
waters may be carried through lead pipes with perfect 
safety, either because the water does not act on the lead 
at all, or because it contains certain mineral matters 
which form a crust, lining the pipes, and protecting 
them from further action. When lead pipes are used, 
the question whether the water acts upon them, should 
be settled by a chemist if necessary. Galvanized iron 
or tin pipes are safer. Water that is constantly running 
through the pipes is less likely to contain much lead 
than that which stands still in the pipes for long periods. 
Lead, when taken in small doses in this way, produces 
its effects very gradually; and the health is often seri- 
ously affected before the cause is discovered. Among the 
symptoms of lead-poisoning are colic, and paralysis of 
certain muscles. 

34. Offensive and poisonous matters, animal and vege- 
table, sometimes find their way into drinking-water, and, 
being dissolved in it, give no sign of their presence. 
Seivage, and the germs of disease, may thus be taken in. 
It is necessary, therefore, to guard the well, or water-pipes, 
very carefully from all impurities. Wells and reservoirs 
are often placed where they catch the drainage from barn- 
yards, or other receptacles for filth. Such drainage will 
go through the soil much farther than is commonly sup- 
posed. The fact that water is clear and sparkling and 
odorless does not prove it pure. A well or reservoir 
should not be located within thirty feet of any filthy spot. 
Even at that distance it is not safe if the ground is porous, 
and slopes toward the well. 



FOOD AND WATER, STIMULANTS, ETC. 87 

Aqueduct-pipes sometimes become leaky, and draw in 
filth. Constant watchfulness against the foes to health, 
which would enter in this way, is necessary. 

EATING AND DRINKING HABITS. 

35. The eating and drinking habits of mankind vary 
greatly. They are modified by climate and by surround- 
ings. The Esquimaux drink fish-oil and eat candles 
with a relish ; the Hindoo lives upon rice ; the Arab sup- 
ports life, and performs great journeys, on a handful of 
grain a day. The European or American requires more 
and better food. The human body can adapt itself won- 
derfully to its circumstances. But those nations, which, 
by reason of their geographical situation and their wealth, 
have been able to obtain the best and most varied diet, 
have the best and strongest bodies. 

36. There is also a great variety in the habits and tastes 
of members of the same race or community. Some pre- 
fer one kind of food, and some another. Some eat two 
meals, and some three. Constitutions, habits, and circum- 
stances make great differences. One man may thrive on 
food that would destroy another. A brain-worker may 
accomplish most and feel best if he eats little until noon : 
a day -laborer would lose his vigor under such a practice. 
One man is over-stimulated by a meat-diet : another ought 
to live chiefly on meat. 

If Nature had not made mankind capable of such vari- 
ations in habit, the work of the world could not be done. 

37. A healthy appetite is Nature's guide to right habits 
of eating and drinking, but Nature intended that appe- 
tite should be controlled and regulated by reason. Each 
man will thus adopt that course which is best for him. 



88 THE HUMAN BODY. 

38. When large bodies of men have to be fed, as in the 
army or navy, it becomes necessary to find out just how 
much of each kind of food a man requires daily. By 
combining physiological reasonings with experiment, Pro- 
fessor Dalton found, that for a man in health, taking free 
exercise in the open air, the following w T as a sufficient 
daily ration : — 

Meat 16 ounces. 

Bread 19 " 

Butter 3J " 

Water 52 " 

Total, water, 3^ lbs. ; solids, 2 lbs. 6| ounces. 

Men at hard labor require more, and those who are en- 
tirely inactive, less. 

STIMULANTS AND NARCOTICS. 

Section II. — 1. Stimulants are substances which excite. 
Narcotics are substances which benumb and stupefy. Some 
substances are both stimulants and narcotics. Alcohol, if 
taken in small quantity, is a stimulant: in large quantity 
it is a narcotic. 

2. Nature supplies us with certain food-stimulants which 
are useful. Stimulant is from a Latin word, stimulus, mean- 
ing a goad. These substances afford little or no nourish- 
ment, but they goad the appetite and the digestive organs 
to greater activity. Such are pepper, spice, and mustard. 
Though good in moderation, they may be used in such 
quantities as to injure the stomach, and make the body 
liable to various disorders. 



FOOD AND WATER, STIMULANTS, ETC. 89 



TEA AND COFFEE. 

3. Tea and coffee are used by all civilized nations. Their 
immediate effect is cheering. They often aid digestion. 
They satisfy the cravings of the stomach, and enable men 
to endure hardship better. But many persons are injured 
by them, — some, because they drink too much; others, be- 
cause they are too susceptible to their action. The morning 
cup of coffee is often paid for by a daily headache. There 
are intemperate tea-drinkers. Tea contains a good deal 
of tannin, which has a tendency to check the action of 
the stomach and bowels. Tea made as the Chinese make 
it, by simply pouring boiling water on the leaves, and 
not steeping long, contains more of the delicate flavors, 
and less of the tannin, than that which is boiled for some 
time. The fact that some healthy people can not go to 
sleep at the usual time if they take a cup of tea in the 
evening, shows that it has a decided effect on the nerves. 
Fretfulness and irritability, and palpitation of the heart, 
are results of its immoderate use. 

4. Coffee, as ordinarily made, contains more solid mat- 
ter than tea, and is, therefore, more nourishing. It has 
less of the astringent principle, and is more soothing. 
Both tea and coffee will sometimes relieve headache. 

It is necessary that the stomach should be very warm 
in order to digest well. If food is taken cold, or if the 
whole body is in a chilly state, the cup of tea or coffee 
awakens the stomach to activity by conveying heat in an 
agreeable form. 

5. Groiving children should drink neither tea nor cof- 
fee. Their fresh and vigorous bodies need no other 
stimulants than air, exercise, and simple food. They are, 



90 THE HUMAN BODY. 

besides, much more susceptible than grown persons to the 
bad effects of these things. 

TOBACCO. 

6. Tobacco is a drug of very great power. A drop of 
the oil extracted from it, placed on the tongue of a dog, 
will kill him almost as quickly as prussic acid. It is 
occasionally used as a medicine, but with caution, because 
its effects are so severe. 

Its odor and taste are disagreeable. When taken for 
the first time, it causes intense nausea and wretchedness. 
By persisting in its use, the revolt of nature is commonly 
overcome, and a liking for it is acquired. Its immediate 
effect is then a feeling of tranquillity and comfort. Sol- 
diers and sailors, and others who have to endure great 
physical labors, find in it support and relief. Students 
use it because it gives them a freer flow of ideas ; men of 
pleasure, because it causes agreeable sensations. In some 
cases it seems to do no harm: in others, its bad effects are 
easily seen. 

7. It diminishes the appetite for food. It sometimes 
causes disease of the mouth and throat. It iveakens the 
stomach. It becomes an absolute necessity: brain and 
stomach demand it. Often the amount used must be 
increased until it is hardly ever out of the mouth. At 
first soothing the nerves, it at last makes them irritable 
and unsteady. 

8. Its effect on the heart is so marked, that the term 
" smokers' heart" is well known to physicians as indicating 
irregular and weak action. The student whose brain is 
rendered more active by it, may find himself suffering at 
length from head- troubles, and failure of nerve-strength; 



FOOD AND WATER, STIMULANTS, ETC. 91 

and he ends his work before his time. The business-man 
who has gone beyond his natural powers, with the aid of 
tobacco, finally breaks down entirely. 

9. It is evident that the effects of tobacco on the young 
are especially evil. Boys who use it are dwarfing their 
minds and bodies. They, are so changing the system 
from its natural healthy condition, that it is preparing 
for disease, and acquiring tendencies that lead to dissi- 
pation and worthlessness. They have no possible excuse 
for its use. 

10. Whatever satisfaction it may give, is purchased at 
the expense of slavery to it, often of personal neatness, and 
at the constant risk of offending companions unused to it. 
In some occupations it is a serious hinderance to success. 

OPIUM. 

11. "Opium" said the great physician Boerhaave, "is the 
finger of God." Whoever has seen or felt the cessation of 
pain that seemed unendurable, under its power, can re- 
spond to his sentiment. Rightly used, it is a boon : per- 
verted to purposes of sensual gratification, it is the cause 
of untold misery. 

12. Opium not only relieves pain, but, in small doses, 
gently stimulates the brain and nerves, making the taker 
able to endure and accomplish more than he otherwise 
could. In larger doses, it induces a dreamy state, in 
which he is released from the annoyances of life, and 
wanders freely on the wings of imagination. In poison- 
ous doses, a stupor comes on, in which the breathing 
becomes slow, sometimes not more than two or three 
breaths being taken in a minute. The pulse is also slow 
and full. When this point is reached, the slumber is likely 



92 THE HUMAN BODY. 

to become deeper until death ensues. To avoid this, it is 
necessary to do every thing to keep the drowsy person 
awake, — to heat and pinch him, to keep him on his feet, 
and walking, to throw cold water on him. 

13. Those who acquire the opium habit become en- 
slaved to it. Its chains are even stronger than those of 
alcohol. The misery which the attempt to go without 
occasions, overcomes the strongest will. The victim be- 
lieves that he will die, that he is dying, and that only 
opium will save him; and, in these circumstances, those 
apparently most conscientious will lie and deceive to obtain 
it. The practice tends to kill truthfulness in the soul, 
and to undermine the whole character. 

14. Opium has a paralyzing effect on the digestive appara- 
tus. It checks the flow of digestive juices, and the action 
of the muscular walls of the bowels. It takes away the 
appetite for food. In those not habituated to it, it com- 
monly causes nausea. "When not under its influence, the 
opium-taker suffers from headache and depression. His 
nerves are relaxed, his mind dull, and his will feeble. He 
is unfitted for the work of life, and his only object is to 
gratify his craving. 

15. Opium should never be taken, except under the direc- 
tion of a physician. Those who are suffering from pains 
which are likely to return and visit them frequently, 
should avoid it. It is better to endure pain than to 
become a victim of the opium habit. 

ALCOHOL. 

16. Alcohol can be made out of any thing that contains 
sugar. It is only necessary to add yeast, or to allow it to 
stand uncovered in a warm place. In raising bread, the 



FOOD AXD WATER, STIMULANTS, ETC. 93 

sugar which is contained in the flour is changed into 
alcohol and carbonic-acid gas. This is fermentation. 
But the heat of the oven causes the small portion of 
alcohol to evaporate. The carbonic-acid gas, after puffing 
up the loaf, and making it light, also disappears. 

17. AVines are the fermented juice of grapes. They 
contain from five to twenty-five per cent of alcohol. 
Brandy, rum, whisky, and gin are distilled liquors, and 
are about half alcohol. Beer, ale, and porter are made 
from grain, and have from three to eight per cent of 
alcohol. Cider is made of apple-juice, and has from three 
to ten per cent of alcohol. The home-made wines, from 
currants, gooseberries, and elderberries, contain a small 
percentage of alcohol. 

18. AVines and liquors are very commonly adulterated. 
The pure article is costly. By adding certain substances 
to an inferior wine, or even to alcohol and water, the taste 
and effect of good wine can be imitated, and a large profit 
made. Beer and porter are adulterated, to make them 
froth, and to improve their flavor and intoxicating quali- 
ties. Some of the substances used are cocculus indicus, 
alum, aloes, copperas, sulphuric acid, mix vomica or 
strychnine, jalap, and lime. 

19. Alcoholic drinks cause a flushing of the skin and 
a feeling of warmth. But they do not maintain the heat 
of the body : they rather lessen it, This has been proved 
by careful experiments, and by the experience of travelers 
in the arctic regions. 

They check the waste and repair that are naturally going 
on. This may be at times an advantage, — in a wasting 
disease, for example. But in health it is much better 
that the natural processes should be undisturbed. 



94 THE HUMAN BODY. 

20. Athletes who are training for hard trials of their 
bodily vigor, abstain from alcohol and tobacco. Disease, 
early failure of strength, and premature death, are the 
results of drinking-habits. Physicians, insurance com- 
panies, and all observing men, testify to this. 

21. It is not always true that the strong liquors are 
most pernicious, nor that the milder drinks are compara- 
tively harmless. In some sections of this country, cider 
is a worse evil than whisky. Its apparent harmlessness 
attracts those who would refuse stronger liquors. When 
the appetite for this drink is awakened, it requires for its 
satisfaction an amount of soaking that keeps the faculties 
benumbed, and reduces the individual to worthlessness 
as surely as more fiery, but less abundant, potations. 

22. It is a melancholy fact, that "the evil that men do," 
in this regard, "lives after them." The iniquities of the 
fathers are visited upon the children. By an inflexible 
law of nature, the effects of alcohol are not expended upon 
the user alone. Morbid cravings for drink, tendencies 
to disease, weakness of body and mind and character, 
are the heritage of misery which he bestows upon his 
offspring. 

23. Chloral is a drug of great value in the hands of the 
physician. It gives sleep to those who can not sleep in 
the natural way. But it is dangerous. It has caused 
death. A habit of using it may be acquired which is 
very injurious to body and mind, and very difficult to 
break. 



FOOD AND WATER, STIMULANTS, ETC. 95 



QUESTIONS. 

Section I. — 1. What is food? 

2. What kinds of material are necessary for the repair of the 
body? 

3. How many elements are found in the body? Name them. 
Give the number of parts in a hundred of the four most abundant. 

4. Name two elements which are found in almost every article 
of food. 

5. Do we need in our food any other elements than the fifteen 
contained in our bodies ? 

6. Where are these fifteen elements found ? Name a great dis- 
tinction between plants and animals. 

7. What is the great work of plants ? 

8. Are all plants food for man? Why not? 

9. What do we infer as to man's food from his teeth? 

10. What article of food is the best combination of the necessary 
elements ? 

11. Of what does man's ordinary diet consist? 

12. Of meats, which is the best? What objection is there to 
pork? What is the value of veal as food? Of lamb? Of mutton? 

13. How does fish differ from flesh ? 

14. Which are the best of the shell-fish ? 

17. What are included in the term " starchy foods "? How many 
parts of starch in a hundred of dried wheat? Of dried oats? Of 
dried rice ? 

18. What do the grains contain besides starch ? What are the 
advantages of the different grains? 

19. What is the most popular vegetable ? 

20. Why are pease and beans valuable ? 

22. Is sugar useful as a food ? 

23. What is butter? 

24. What is the use of cooking? 

25. What is the danger in eating meat raw? 

26. What gain is there in cooking starchy foods ? 

27. What are the essential points for good bread ? 

28. What makes bread light f What makes bread heavy? What 
makes bread sour? 



96 THE HUMAN BODY. 

29. Why is not pie-crust as digestible as bread? Why is food 
fried in fat indigestible ? 

31. What mineral do we take pure? Are mineral matters 
changed by digestion ? 

32. What is the proportionate amount of water in the body ? 

33. Is drinking-water ever absolutely pure? What sometimes 
happens to water which is carried through lead pipes? What 
kinds of pipes are safer ? What are symptoms of lead-poisoning ? 

34. How far must a well be from all filth to be safe ? Is it always 
safe at that distance ? How may aqueduct-pipes become dangerous ? 

35. Can the body adapt itself to different habits of eating and 
drinking ? 

36. Do the same rules for eating and drinking always apply to 
all? 

37. What is nature's guide to right habits of eating and drinking? 
Is the appetite always healthy ? 

38. Under what circumstances is it necessary that a large num- 
ber of people should adopt the same habits of eating and drinking? 
What is a sufficient amount of food daily for a man ? 

Section II. — 1. What are stimulants ? What are narcotics ? Is 
the same thing ever both a stimulant and narcotic ? 

2. What service does a stimulant render in digestion ? 

3. What is the immediate effect of tea and coffee? Are they 
ever injurious? 

5. Should growing children use them ? 

6. What is the first effect of tobacco ? What are its later effects ? 

7. What is its effect on the appetite? on the stomach? On the 
nerves ? 

8. What is its effect on the heart ? 

9. Have boys any good reason for using tobacco ? 

11, 12. What is the effect of opium in small doses ? In large 
doses ? 

13. What is the effect of the opium habit on the moral nature ? 

14. What is the effect of opium on the digestion ? 

15. Under what condition only may opium be rightly used? 

16. What does alcohol come from ? 

17. What is wine ? How much alcohol does wine contain ? What 



FOOD AND WATER, STIMULANTS, ETC, 97 

are brandy, rum, whisky, and gin ? How much alcohol do they 
contain? What are beer, ale, and porter? How much alcohol do 
they contain? What is cider? How much alcohol does it con- 
tain ? Do home-made wines contain alcohol? 

18. How are the purchasers of wines and liquors defrauded? 

19. Does alcohol keep up the heat of the body? What is its 
effect on the processes of waste and repair ? 

20. What is the general testimony as to the effects of alcohol on 
the health ? 

21. Is it true that only the stronger liquors are hurtful ? 

22. What is the effect of alcohol on the children of the drinker ? 

23. Under what condition only should chloral be used ? 



98 THE HUMAN BODY. 



CHAPTER VII. 

DIGESTION AND ABSORPTION. —THE 
LYMPHATIC SYSTEM. 

Section I. — 1. Food repairs the waste of the bocty, and 
keeps up life. If asked how it is made to do this, you 
could answer, " It is eaten." By that, you mean that it is 
taken into the mouth, and chewed, and swallowed. But 
if asked again, What becomes of it after it is swallowed, 
and how does it get into our bones and flesh and brains, 
and keep every particle living, and perhaps growing, you 
could not answer without study. For, in health, we know 
nothing about our food, by our feelings, after it is swal- 
lowed. 

2. If, however, we examine into the matter, we find that 
the food, after being swallowed, passes on down a tube 
which extends through the whole length of the trunk, be- 
ginning at the lips. This tube is the alimentary canal. 

3. The alimentary canal is about twenty-seven feet long, 
in a man. In order to get it into the trunk of the body, 
which is only about two feet long, a portion of it is coiled 
up in a mass. This portion we call the bowels. 

4. Most of the canal is about an inch and a half wide. 

Suggestions to Teachers. — 1. An emulsion can be made with oil and 
the white of an egg, or with mucilage obtained from the druggist's. This 
can be compared with a mixture of water and oil. 

2. A tube made of chamois leather, or a cone of filter-paper, will illus- 
trate the soaking through membranes. 



DIGESTION AND ABSORPTION. 



99 



In two places it spreads out, as a brook spreads into 
pond. One of these en- 
largements is the stom- 
ach ; the other, the large 
intestine. 

5. One layer of the 
wall of the canal is in- 
voluntary muscle. Part 
of the fibers run length- 
wise, and part crosswise ; 
and they surround the 
tube. 

6. The canal is lined 
by mucous membrane. 
Mucous membrane can 
be seen on the walls of 
the mouth. It is quite 
like the skin in struc- 
ture, but differs in being 
soft and moist and red. 
The mucous membrane 
lines the alimentary 
canal, and other cavities 
in the body, just as the 
skin covers the outside. 

7. We have been 
speaking of the alimen- 
tary canal as a whole. 
Different portions of it 

have Special names, down. — I. (Esophagus. 2. Stomach. 

1^1 n j j- ii intestiue. 4. Large intestine. 

he first portion is the B 

mouth. Then we come to the throat ; then to the oesophagus, 




Fig. 37. 

Alimentary Canal from the (Esophagus 

3. Small 
intestiue. 



100 THE HUMAN BODY. 

or gullet; then to the stomach, which lies at the lower 
border of the ribs, in front; then to the small intestine, 
which is twenty feet long, coiled in the lower part of the 
abdomen ; then to the large intestine, which is five feet 
long, and ends the tube. 

DIVISIONS OF THE ALIMENTARY CANAL. 

1. Mouth. 4. Stomach. 

2. Pharynx (Throat). 5. Small Intestine. 

3. (Esophagus (Gullet). 6. Large Intestine. 

8. Each of these divisions of the canal has its own 
peculiarities, and each has its own part of the work of the 
whole to do. This work is called digestion. 

9. By digestion, we mean the changes that take place in 
the food, as it passes through the alimentary canal, by 
which it is fitted to be taken into the blood. 

10. The need of such changes is very plain. We could 
not imagine that the food, in the condition in which it is 
eaten, could be taken into the blood. There are no open- 
ings from the canal into the blood-vessels. Nothing can 
get out of it into the rest of the body, unless it can soak 
through its walls, as water would soak out of the finger 
of a glove if it were poured into it. To do this, the food 
must be dissolved. 

11. A lump of sugar or salt will dissolve in water ; but 
a piece of meat, or a cooked egg, or oatmeal, or man} 7 other 
articles of food, will not. All such articles must be changed 
in the alimentary canal, so that they will dissolve in water. 

12. We find, accordingly, that from the walls of the 
canal, and from certain organs called glands which lie 
just outside of the canal, and communicate with it by 



DIGESTION AND ABSORPTION. 101 

tubes, juices are poured out, called digestive juices, which 
mix with the food, and make in it the very changes that 
are required. These juices differ from each other, and 
come into different portions of the canal. One juice acts 
on one kind of food, and another juice on another kind. 

13. The butter and cream, and all the other fats, that we 
eat, are acted on in a way peculiar to themselves. They 
are not really made to dissolve in water; but a juice is 
furnished, called the pancreatic juice, with which they 
are so thoroughly mixed, that they Avill pass through that 
part of the wall of the alimentary canal which is their 
special way out. 

14. There are some other fluids, besides this pancreatic 
juice, that oil will mix with; and such mixtures are called 
emulsions. Milk is an emulsion. The oil-globules dif- 
fused through it rise to the top, and make the cream; and 
from the cream we make butter, by the method already 
described (Chap. VI., Sect, I., 23). We eat the butter. It 
passes dow r n, without being changed, until it reaches the 
place where the pancreatic juice comes in. With that it 
mixes ; and all these little oil-globules are separated 
again, and diffused through the fluid, just as they were at 
first in the milk. This fluid is the chyle; and it looks 
so very like milk, that the little hair-like tubes that carry 
it away, after it has passed through the wall of the canal, 
are called lacteals, or milk-vessels. (Latin, lac, milk.) 

15. The muscle in the walls of the canal has a good deal 
to do with digestion, as well as the juices inside. It acts 
in two ways : it forces the food along, and it kneads and 
mixes it with the juices. We know how the muscles of 
the mouth and throat close about it, when we swallow. 
These are voluntary muscles, and we are conscious of their 



102 THE HUMAN BODY. 

action. When it gets below the throat, the muscles are 
still contracting around it and behind it, pushing it on, as 
we strip water from a soft tube by drawing it between our 
fingers. But these are involuntary muscles, and we are 
not conscious of their action. While it remains in the 
stomach, the muscles are constantly "working" it, very 
much as a baker works his bread to mix the yeast with 
it. The same processes continue through the small and 
the large intestine. 

If the juices are too scanty, or poor in quality, diges- 
tion does not go on well. If the muscle of the walls of 
the canal is weak or sluggish, digestion does not go on 
well. These conditions are called dyspepsia. 

16. What has been said of the changes in the food, that 
constitute digestion, may be summed up as follows: The 
fats are made into a fine emulsion. The other kinds of 
food are changed into substances that easily dissolve in 
the fluids of the canal. 

THE TEETH. 

17. Let us examine more particularly the different 
parts of the digestive apparatus. Just behind the lips, the 
outer gates of the alimentary canal, stand the inner gates, 
the teeth. A child of about five years of age, who has not 
yet lost any of his first teeth, has twenty in all, ten in each 
jaw. If we could look deep into his jaw-bones, we should 
see, beneath these twenty, twenty-eight more, — buds of 
teeth, so to speak, which are his second set (all but four), 
almost ready to grow out, So that, at that age, a child 
has really forty-eight teeth, — more than at any other time 
in his life. 

18. The first set are, — 



DIGESTION AND ABSORPTION. 103 

Eight incisors (cutters), four front teeth above and 
below. 

Four canines (Latin, canis, a clog), next to the incisors. 

Eight molars (Latin, mola, a mill), grinders, back 
teeth. 

The incisors are chisel-shaped, and intended for cutting, 
not for chewing. 

The canines correspond to the long, pointed fangs of 
a dog, and are made for piercing and holding on to 
things. 

The molars are broad and blunt, and are made for 
grinding up food. 

19. The second set, the last of which do not appear before 
the age of seventeen years, comprises 

Eight incisors, four front teeth above and below. 

Four canines, next to the incisors. 

Eight bicuspids, next to the canines. 

Twelve molars, back teeth. 

The first set come out, one by one, between the ages of 
five and fourteen years; and the second set appear one 
by one as the first are lost, The wisdom teeth are the 
last to appear, at some time after seventeen years of age. 

20, Animals that live wholly on flesh, like the tiger, 
have no grinders, but only cutting-teeth. Their jaws do 
not move from side to side, but only up and clown, like 
shears. On the other hand, animals that live wholly on 
vegetable food have many broad grinders, and not so 
many cutting-teeth in proportion; and their jaws have a 
motion from side to side, as well as up and clown. Man 
is well provided with both kinds of teeth, which goes to 
prove that he was made to live on both vegetable and 
animal food. 



104 



THE HUMAN BODY. 



Neck. -V 



Root. 




Fig. 38. 
Incisor Tooth sawed 



21. A tooth is made of a substance like bone, called 
dentine. At the end of the root, a very small hole can 
be seen. This is the entrance to a canal 
which runs through it lengthwise, and 
contains the tiny nerve and blood-vessel 
which supply it. The root is fixed in a 
socket in the jaw-bone. The crown, or 
body, projects beyond the gums. The 
neck is at the junction of crown and root. 
The crown is covered by enamel, which 
is the hardest substance in the body. 

22. It is the work of the teeth to bite 
off mouthfuls of food of the right size, 
and then to grind them up fine. This 
is the first act in digestion. When food 
is well ground, the juices of the stomach easily mix with 
it, and act on it. If the teeth are gone, or if food is bolted 
without being chewed, it enters the stomach in lumps, 
which the juices can not easily pene- 
trate. When food is not soon acted on 
by the digestive juices, it becomes sour, 
and makes gases, which distend the 
stomach, and often give pain. 

23. The teeth stop growing after 
they have taken their places; and, if 
they are chipped, they do not heal. 
They may be injured, — 

1. By very hot or very cold substances. 

2. By some medicines, 
s. By decomposing food between them. 
They should be brushed every day, and cared for by a 

dentist if unsound. Good health and good looks both 
depend much on them. 



Enamel. 



Dentiue 




Fig. 39. 

Molar Tooth sawed in 

two. 



DIGESTION AND ABSORPTION. 



105 



THE SALIVARY GLANDS. 

24. In health, the mouth is always moist. When we 
taste any good thing, or even think of it, the " mouth 
waters." This water is the saliva, or spittle; and most of 
it comes from bodies called the salivary glands. 

25. There are three pairs of these glands, — two parotid 
glands, two submaxillary glands, and two sublingual 
glands. 




Salivary Glands. 



Fig. 40. 
■ 1. Parotid gland. 2. Submaxillary gland. 



3. Sublingual gland. 



The parotid gland is the largest, and is situated just 
under the ear. Mumps is an inflammation of this gland, 
which makes it swell, and the neighboring parts of the 
neck with it. 

The submaxillary gland is next in size, and lies behind 
the edge of the under jaw beneath the floor of the mouth. 

The sublingual gland lies farther forward than the sub- 
maxillary, also under the floor of the mouth. 



106 THE HUMAN BODY. 

26. Each one of these glands has one or more tubes, 
called ducts, opening into the mouth. The duct of the 
parotid gland opens on the inside of the cheek. The ducts 
of the submaxillary and sublingual glands open under 
the tongue. 

27. These glands make the saliva from the blood which 
passes through them. The saliva moistens and softens 
the mouthful of food, coats it over, so that it will slip 
down the canal, and to some extent dissolves it. When 
the mouth is absolutely dry, it is almost impossible to 
chew or swallow any thing. 

THE STOMACH. 

28. The stomach is a portion of the alimentary canal 
about twelve inches long, expanded into a pouch. It lies 
at the lower border of the ribs in front, more on the left 
side than on the right. When it is empty, it collapses, like 
any other bag. When it is full, it extends down below 
the ribs; and, as it lies directly under the heart, it some- 
times presses up, and makes the heart feel crowded. 

29. This pouch, like the rest of the alimentary canal, is 
lined with mucous membrane, somewhat like the lining 
of the mouth. If this membrane is examined with a lens, 
innumerable little holes appear: so small, and so close 
together, are they, that it has been estimated that there 
are five millions of them in all. These are the mouths 
of little pits that dip down in the membrane. Some of 
these pits are shaped like the finger of a glove: others 
have side-branches, like several glove-fingers opening into 
one central finger. These are the glands of the stomach, 
which make the gastric juice. When food enters the 
stomach, this juice wells up from the pits until a drop 



DIGESTION AND ABSORPTION. 



107 



stands at the mouth of each one. This overflows, and 
another follows; and so it keeps coming, until there is 
just enough to mix with the food taken. Then it stops. 
Meantime the muscular walls have been turning and 
squeezing the food, some- 
what as the teeth and 
tongue do in the mouth. 

30. The outlet of the 
stomach is at its right 
end, and is guarded by 
the pylorus (from a Greek 
word, meaning keeper of 
the gate). This pylorus 
is a ring of muscular 
fibers, which surrounds 
the canal, and, by con- 
tracting, closes it. Its duty 
is, to let no food pass out until it has been properly acted 
on by the stomach. When the food is hard and indigest- 
ible, the laboring stomach often becomes exhausted and 
distressed. It w r ould fain get rid of its contents : but the 
pylorus steadfastly resists, until vomiting occurs; or else, 
this resistance being overcome, the troublesome matters 
pass down, to cause similar discomfort in the intestines. 

31. Near the beginning of the small intestine, two little 
tubes open into it by the same orifice. If w r e follow these 
back a short distance, one will lead us to the liver, the 
other to the pancreas. 




Fig. 41. 
Stomach Glands of a Pig. 



THE LIVER. 



32. The liver is a large organ situated at the lower 
border of the ribs, on the right side. It is a gland, and it 
does three things : — 



108 



THE HUMAN BODY, 



li It helps to purify the blood, by taking out of it certain 
substances. 

2. It makes glycogen. Glycogen is a food substance, made 
of the food we eat, and stored up for a time in the liver, 



Liver. 



Gullet, Pancreas. 



Gall 
bladder 




Small intestine. 

Fig. 42. 
The Liver and other Organs of Digestion. 

somewhat as starch is stored up for the use of a potato- 
plant in the potato. 

3. It makes bile. 

33. So large an organ as the liver must have a very 
important work, When the flow of bile is cut off, the- 



DIGESTION AND ABSORPTION. 109 

flesh is rapidly lost, and death ensues. Sometimes the 
duct of the liver gets clogged. The yellow stream of bile 
is dammed up, and forces itself into the blood-vessels, and 
is carried all through the body. It colors the skin and 
eyes yellow. This condition is called jaundice. 

The bile in the intestine mingles with the other diges- 
tive juices, and with the food, and aids digestion in sev- 
eral ways. 

34. The pancreas lies across the backbone, just behind 
the stomach. It is only one-twentieth as large as the 
liver. It is a mass of little tubes, in which the pancreatic 
juice is forming during digestion. These little tubes 
empty into one large tube, which runs through its whole 
length, and finally discharges into the intestine, just as 
the small drain-pipes in the houses of a town empty into 
the large main in the street, and that, finally, into the 
river. 

35. The pancreatic juice makes a mixture, called an 
emulsion, of the fats, in which they can easily pass 
through the walls of the canal. It also aids in dissolving 
other parts of the food. 

36. The lining of the whole length of the small and 
large intestines contains little pits similar to those which 
are found in the stomach. A fluid called the intestinal 
juice, which helps digestion, wells up out of them; but 
the action of this fluid is not so important as that of the 
gastric juice. 

37. Recapitulation. The digestive apparatus consists 
of the alimentary canal, and certain glands connected 
with it, 



110 



THE HUMAN BODY. 



Divisions of the canal 



In the canal 



Digestive 
glands, 



Mouth (containing teeth and tongue). 

Throat. 

Gullet. 

Stomach. 

Small intestine. 

Large intestine. 

Stomach glands, making gastric juice. 

Intestinal glands, making intestinal juice. 



Outside the 
canal . . 



Parotid, 
Salivary glands, \ Submaxillary, 

Sublingual, 
Liver, making glycogen and bile. 
Pancreas, making pancreatic juice. 



making sa- 
liva. 



ABSORPTION. 

Section II. — 1. The alimentary canal may be likened 
to the kitchen in which the food is prepared. The blood 
is the carrier, swiftly moving through the passage-ways, 
and serving every room in the house of life. 

2. Through the whole length of the canal, its wall is 
filled with meshes of hair-like blood-vessels, completely 
surrounding it, like a net-work, ready to soak up the food 
through their thin w T alls just as fast as it is made ready. 
Through these little vessels the current is moving, so that 
fresh blood is continually taking the place of that which 
has just passed on with its load. 

3. Let us follow a mouthful of food, consisting of bread 
and meat, from its entrance between the lips into the 
canal. First the teeth cut and grind it, the tongue and 
cheeks skillfully turning and shifting it from side to side, 
the saliva, meantime, wetting and partly dissolving it. 
When it is fine and soft enough, the tongue forces it 
against the roof of the mouth, and so slips it back to the 
throat. Certain muscles then contract, and lift the throat 
up around it. It is clasped and pushed down by the con- 



DIGESTION AND ABSORPTION 



111 




traction of successive rings of muscular fibers, through 

the gullet into the stomach. There it 

remains for a time. It has not been 

long in the stomach before portions of 

it are digested, and these begin to pass 

through its Avails. Other portions are 

not digested by the gastric juice. But 

the whole is reduced to a fluid-like 

gruel, and then passes the pylorus 

into the small intestine. In this state 

it is called chyme. Here it meets the 

bile and the pancreatic juice. These 

mix with the fat, and make an emul- 
sion which is called chyle. The rest 

of the food is also changing, and being 

dissolved out of the branny and fibrous 

parts which can not be digested. 

4. In the lining of the small intestine, we find a special 

apparatus for absorption; and it is here that absorption 

goes on most actively. 

This lining has a soft look, 
like veh^et. With a micro- 
scope we can see that the 
reason that it looks so, is, that 
it actually has a nap, like 
velvet. This nap is made of 
innumerable short, thread- 
like projections, which are 
called villi (Latin, villus, a 
tuft of hair). 

5, Each villus contains a 

net-work of fine blood-vessels, and, also, one of another 



Fig. 43. 
Villi of the Small In- 
testine Magnified. 




Fig. 44. 
Showing the Vessels in Villi. 



112 THE HUMAN BODY. 

kind of vessels called lacteals, which will be described 
presently, whose special work it is to take up fat. 

6. As the muscular walls of the intestine contract and 
relax, these little villi are worked in the mass of food; 
and they draw in the digested part as the fine rootlets of 
a plant draw up liquid nourishment from the earth in 
which they stand. 

7. As the chyme and chyle pass on down the small 
intestine, the digestible portion is constantly growing 
less, until at length it has all been taken up, — the chyle 
chiefly by the lacteals, and the other portions of the 
food chiefly by the blood-vessels; and what remains is 
indigestible and useless. 

8. The food, having thus become a part of the blood, is 
carried through the body, and permitted to soak out 
through the walls of the capillary vessels, to feed each 
particle of living substance. 

9. Water, and mineral matters like salt, that are dis- 
solved in water, need no digestion, and are taken up by 
the vessels in all parts of the canal. 

Section III. — The lymphatic system. 1. This is a 
system of tubes and glands, — the tubes resembling the 
blood-vessels in some respects. They begin with hair-like 
tubes running among the capillaries, and much like them. 
These unite to form larger tubes, which unite with others, 
and so on, until they have all been united into two tubes, 
each about as large as a slate-pencil. These open into the 
large veins, not far from the heart, They are called the 
thoracic duct and the right lymphatic duct. 

2. But the lymphatic system is not just like the system 
of blood-vessels. The lymph, as the fluid which they con- 



DIGESTION AND ABSORPTION. 



113 



tain is called, does not "circulate." The blood starts from 
the heart, and is brought around back to the heart again. 
The lymph starts from all parts of the body, and is 



i< 




Fig. 45. 
Lymphatics. — 1. Lymphatic ducts. 2. Lymphatic glands. 



brought in toward the heart, If you compare the lym- 
phatic vessels with the capillaries and veins, you have 
nothing in this system to correspond with the arteries. 



114 



THE HUM AS BODY. 



The lymphatic vessels are much more delicate and 
slender than the blood-vessels. 

3. When a farmer has a wet field, he frequently lays 
pipes in it made of burned clay, called tile. The standing 
water soaks into these pipes, and is carried off; and so 
the field is dried. 

The lymphatics are the drain-pipes of the body. They 
assist the blood-vessels in taking up the fluids which are 
standing in all parts, and carrying them away to be 
delivered up to the blood-stream at the proper place. 

4. The lacteals comprise that portion of the lym- 
Aorta phatic vessels that 



p Thoracic 
' \duct. 



Lymphatic 
glands. 




W?\% .Small 



Lacteals. 

Fig. 46. 
Lymphatics of the Intestine. 



begins in the walls 
of the small intes- 
tine. When diges- 
tion is not going on, 
they are drain-pipes, 
like the rest. As 
soon as digestion 
begins, they begin 
to look white and 
milky. They are 
then engaged in 
their special work of 
taking up the fat 
from the intestine. 
They are found in 
all the villi. 



Section IV. — 1. 
control of the will. 



we give no thought to it. 



The process of digestion is not under 
In health it takes care of itself,. and 
But, when the digestive appa- 



DIGESTION AND ABSORPTION. 



ratus is weak or disordered, it becomes the seat of almost 
constant pain and discomfort. The appetite is lost, the 
strength fails, the nerves become irritable, and the brain is 
clouded. It is important, therefore, to know what helps or 
hinders it. 

HINDERANCES TO DIGESTION. 

1. Eating too fast. In this case, the food is taken down 
without being prepared by chewing. 

2. Strong excitement. Sudden fear, anger, or grief takes 
away the appetite, and stops the flow of the digestive 
juices. 

3. Great fatigue. No careful horse-owner will feed his 
animal immediately when he comes in tired and heated. 
Food swallowed under such circumstances will be digested 
with difficulty by a man or a horse. 

4- Mental effort. It is not well to read, or to study during 
a meal. The mind should be at rest, and some degree 
of attention should be given to the food. 

5. Too much food. Evidently there is a limit to the 
amount of food that can be digested. The stomach may 
be so full that it can not easily move its contents. The 
quantity may be so great that the digestive fluids can not 
fully permeate them. Those parts of the mass which are 
not digested will soon decompose, producing acidity, and 
a pressure of gas. 

6. Too much liquid with food. A good deal of water is 
directly absorbed. But, when too much is taken, some 
remains in the stomach, and so dilutes the gastric juice, 
that it is weakened. 

7. Very cold substances, as ice-water, taken with food, will 
sometimes stop digestion. The gastric juice acts best in a 



116 THE HITMAN BODY. 

temperature of about a hundred degrees. Stomachs, how- 
ever, differ in their ability to withstand cold as much as 
the outer parts of the body. 

8. Irregularity in eating. The digestive apparatus is 
subject to habit, like the rest of the system. At the ac- 
customed meal-time, the saliva and the other digestive 
fluids will flow, though no food is taken. When that time 
is passed, they do not start so readily. 

9. Lack of exercise. In a sluggish condition of the body, 
the digestive juices flow slowly. The alimentary canal 
does not contract vigorously to knead the food. 

io. In applying these principles, it is to be remembered 
that one person can do without harm, and sometimes with 
advantage, what is injurious to another. Men differ very 
widely in their habits. Each should understand the 
facts and principles of physiology, and apply them, with 
the aid of experience, to his own case. 



EFFECTS OF ALCOHOL ON DIGESTION. 

Section V. — 1. Alcohol irritates the mucous mem- 
branes. You could not hold it in your mouth; and, if 
you should swallow any of it clear, your stomach would 
seem burned. When mixed with much water, as it 
is in wines and liquors, it is less fiery, and the sensa- 
tions produced in the mouth and stomach may be agree- 
able. 

2. It is by this irritant quality that it injures the 
stomach. In the famous case of St. Martin, the inside of 
whose stomach could be observed through a wound, Dr. 
Beaumont found that " the free use of ardent spirits, wine, 
beer, or any of the intoxicating liquors, when continued 



DIGESTION AND ABSORPTION. 117 

for some days," constantly produced "a state of inflamma- 
tion and ulceration in the lining membrane, and change 
of the gastric juice." At the same time, St. Martin suffered 
no pain, or other sensations, which indicated the true state 
of things. 

Examinations of the stomachs of drinkers, after death, 
show the same conditions. 

3. One of the most wonderful things about our bodies 
is, that they will change so as to suit the conditions in which 
they are. If a man has to work with his arms, they grow 
large and strong. If the skin is exposed to the weather, 
or to chafing, it loses its smoothness, and becomes hard. 
The stomach was made to digest wholesome food. If a 
man insists on making it a receptacle for burning liquors, 
Nature straightway begins to adapt it to that use. The 
delicate membrane grows tough. The mucus which nat- 
urally moistens it becomes thick and ropy, so as to protect 
the surface. Some of the little glands which pour out 
the gastric juice are destroyed. Those which remain are 
unhealthy. If the process is carried far enough, he has a 
pouch which gladly receives alcohol, but its usefulness as 
a stomach is greatly impaired. 

4. If we put in a test-tube some gastric juice from the 
stomach of an animal, and add alcohol to it, a white 
powder appears, and settles to the bottom. This is pepsin, 
which gives the juice its power to digest. Alcohol sepa- 
rates it from the juice; so the drinker, with a stomach 
perhaps already weak, is adding to his gastric juice that 
which destroys, for the time, what activity it has. After 
the alcohol passes out of the stomach, the pepsin is 
dissolved again. 

5. The effect of alcohol on the intestine is similar to 



118 THE HUMAN BODY. 

that on the stomach, but much less ; because most of it is 
absorbed before reaching that part of the canal. 

6. Alcohol is carried to the liver by the blood. 
Alcohol irritates the liver, and causes an overfullness of 

its blood-vessels. 

Alcohol often excites inflammation of the liver. This 
is followed by various changes, one of the most notable 
of which is a contraction into a hard, knobbed mass, 
called, in medical works, gin-drinker's liver. 

7. Thus the power of digesting food, which is the source 
of health and strength, is assailed by alcohol at two im- 
portant points, — in the stomach, and in the liver. 

8. The effect of alcohol on the kidneys may be referred 
to here, because it is similar to its effect on the liver. The 
kidneys are purifying organs. The blood is constantly 
passing through them, and they filter out of it waste 
matters. Blood charged with alcohol irritates them, and 
excites, frequently, a slow inflammation, which results in 
their destruction. This is one of the forms of Bright's 
disease, and in most cases is incurable. 

9. These effects do not always follow the use of alcohol, 
but in very many cases they do. They are the possibili- 
ties and dangers of the drug. 



QUESTIONS. 

Section I. — 1. Why do we need food? 

2. What is the alimentary canal ? 

3, 4. What is its length and diameter ? 

5. What important tissue in its wall ? 

6. What is mucous membrane ? 

7. Give the divisions of the alimentary canal. 



DIGESTION AND ABSORPTION. 119 

9. What is digestion ? 

10. Why is digestion necessary ? 

11. Is all our food easily dissolved? 

13, 14. How are fats digested ? What is an emulsion ? What are 
the lacteals ? What is chyle ? 

15. What has the muscle of the alimentary canal to do with 
digestion? Is it voluntary, or involuntary? 

16. What are the changes that constitute digestion ? 

17. How many sets of teeth do we have ? When do we have the 
largest number of teeth in our jaws ? 

18. Give the number and names of the first set. 

19. Give the number and names of the second set. 

20. How do the teeth indicate the habits of the animal ? 

21. What is the structure of a tooth ? 

22. What is the work of the teeth ? 

23. How may the teeth be injured ? 

24. How is the mouth kept moist ? 

25. Name the salivary glands. Give their location. 

26. Wliat are their outlets ? 

27. What is the use of saliva ? 

28. Where is the stomach situated? 

29. Describe the glands of the stomach. How is the gastric juice 
mixed with the food ? 

30. What is the pylorus ? 

31. What two large glands are connected with the upper end of 
the small intestine ? 

32. Where is the liver situated? What three things does it 
do? 

33. What is jaundice? What does the bile do? 

34. Where is the pancreas? What is its structure? 

35. What does the pancreatic juice do ? 

36. What glands are there in the walls of the small and the large 
intestine? What is the fluid that comes from them called, and 
what is its use ? 

37. Give the divisions of the alimentary canal. Enumerate the 
digestive glands in the canal. What is their product? Enume- 
rate the digestive glands outside of the canal. What is their 
product ? 



120 THE HUMAN BODY. 

Section II. — 1, 2. How is digested food carried through the body? 

3, Follow a mouthful of food in its progress through the alimen- 
tary canal. 

4, What special apparatus for absorption in the small intestine ? 

5, 6, 7. Describe its action. 
9. Is water digested ? 

Section III. — 1. What is the lymphatic system? What are the 
names of the tubes in which the lymphatic vessels terminate? 

2. State the difference between the lymphatic system and the 
circulating system. 

3. What is the use of the lymphatics? 

4. What are the lacteals ? 

Section IV. — Name some hinderances to digestion. 

Section V. — 1. What is the effect of alcohol on the mucous 
membrane? 

2. What was its effect on the stomach of St. Martin ? 

3. How does the stomach adapt itself to alcohol? 

4. What effect has alcohol on the gastric juice? 

5. What effect on the intestine? 

6. How does alcohol reach the liver? and how does it sometimes 
affect it? 

8, What is the effect of alcohol on the kidneys? 



RESPIRATION AND THE VOICE. 121 



CHAPTER VIII. 
RESPIRATION AND THE VOICE. 

Section I. — Air. 1. We have studied the processes of 
digestion and absorption, by which food and water get 
into the blood, to be distributed through the body. It 
remains to study the method by which air is taken in and 
used. The process is called respiration. 

2. We live in air, and we can not live out of it any 
more than fishes can live out of water. We can not see 
the air, but we can feel it. When it is moving very 
rapidly, it has great force. It can root up trees, and 
carry away houses. If we could see it, it would appear 
like water. When the wind is blowing, we would see a 
stream of it pouring across the country like a river, or 
like a flowing sea. 

Suggestions to Teachers. — Section I. A few chemical experiments 
will illustrate this section. Show the effect of oxygen and of carbonic-acid 
gas on a burning candle. Fill a test-tube with lime-water, and breathe into 
it to demonstrate carbonic-acid gas by the formation of a milky precipitate 
of carbonate of lime. 

Section II. Show, if possible, a fish's gills. Illustrate by drawings; 
by a bunch of grapes, etc. Get a piece of lung from the butcher's, or, still 
better, the lungs and air-passages of some small animal. 

Section III. The nasal cavities should be shown, either in the human 
skull, or in that of a sheep or other animal. 

Section IV. Simple experiments with the apparatus mentioned in the 
text, will illustrate the principles. 

Section VI. Show the moisture in the breath by breathing on glass. 

Section VII. A larynx can easily be got from a butcher, and the glottis 
and vocal cords and muscles can be shown. 



122 THE HUMAN BODY. 

3. Air is a material substance, though invisible. It is 
in the gaseous condition. It is composed chiefly of three 
gases mixed. 

COMPOSITION OF AIR. 

Nitrogen, about 79 parts in a hundred. 

Oxygen, about . . . .21 " " 

Carbonic-acid gas, about . . .04 " " " 

Besides, there is watery vapor, and a little of various other 
substances. 

4. Nitrogen gas, which constitutes nearly four-fifths of 
the air, is not used either by animals or plants. Neither 
is it injurious. Its office is to dilute the oxygen. If we 
put a lighted candle into a jar containing pure oxygen, it 
will burn up very rapidly. So, if an animal is made to 
breathe pure oxygen, it is greatly excited; and its life, 
which is partly a burning, is quickly burned out. The 
nitrogen in the air dilutes the oxygen to just the right 
strength. 

5. Carbonic-acid gas is not used by animals. On the 
other hand, they are constantly throwing it off as a waste 
product. But plants live on it: it is a large part of their 
food. As they take it in, they give off oxygen. 

Animals take in oxygen, and give out carbonic-acid gas. 

Plants take in carbonic-acid gas, and give out oxygen. 

Fires, and the decay of animal and vegetable matters, are 
adding constantly to the carbonic-acid gas. But there is 
only one process which is adding to the oxygen ; and that 
is, the action of the leaves of plants. On the whole, the 
addition and subtraction are equal. The amount of car- 
bonic-acid gas in the whole air remains the same, though 
in a smoky city it is greater than it is in the country. 



RESPIRATION AND THE VOICE. 123 

Fires ) 

Decaying matters y add to the carbonic-acid gas. 

Living animals 

Living plants add to the oxygen. 

6. Oxygen is the most remarkable of the elements. 
Three-fourths of the material of which our bodies are 
made is oxygen: eight-ninths of the material of which 
water is made is oxygen. It is more than half the weight 
of many other substances. We can not live five minutes 
without a fresh supply of it. It is infinitely more valu- 
able than gold, but is free to all. We do not have to 
work for it, as we do for food: we take it from the air we 
breathe. 

THE LUNGS. 

Section II. — 1. The whole of the air that we take in 
does not enter the blood. Just as the digestible parts of 
our food are absorbed, while the indigestible parts are 
cast out, so that part of the air that we need, which is 
oxygen, is absorbed in the lungs, and the rest is breathed 
out. 

2. The lungs are masses of little cells, with very thin 
walls, placed in the chest. On the outside of the walls of 
these sacs are the capillaries, — millions of them. They 
cover the sacs as the netting covers a balloon, only they 
are much closer than such a net. The blood from the 
pulmonary artery pours into these capillaries, and so 
spreads out all over the lung-cells. The oxygen, then, has 
only to pass through the thin lung-cell and the thin capil- 
lary wall to enter the blood. 

3. Frogs get a part of their oxygen through their skins. 
These are delicate and moist, and just beneath them the 
net-work of capillaries is spread out. Oxygen easily 



124 



THE HUMAN BODY, 



passes through. As there is considerable air dissolved in 
the water, they can live under it all winter on what oxy- 
gen they can take in from it through their skins. Man's 



LUDg.. 




Lung. 



iilli Pericardium - 



Fig. 47. 
Lungs in Position, the Wall of the Chest being cut away. 

skin is thicker, and does not allow the oxygen to pass 
through. 

4. Fishes have a peculiar way of getting their oxygen. 
They, of course, must take it from the air which is dis- 
solved in the water. On each side of their throats they 




RESPIRATION AND THE VOICE. 125 

have an opening, in which are a number of flat plates 
of membranes, called gills, with net-works of blood-ves- 
sels in them. The water is swallowed, and 
passes out between the plates through these 
openings. The oxygen which it contains 
enters through the thin membranes into 
the vessels. 

5. Other animals take in oxygen in a 
different way. But, though the way is dif- 
ferent, the principle is the same. In every GlLL ff; AN Eel# 
case, the capillary vessels are spread over 

a thin membrane; and the air is on the other side of 
that membrane. 

6. In some of the lower animals, the lung is a single 
sac, like a bladder, with the capillaries on the outside. 
In man, instead of being a single sac, each lung is a vast 
number of very small sacs bound together in a mass, with 
fine blood-vessels and air-tubes surrounding and connect- 
ing them. 

Imagine a bunch of grapes with the contents of each 
grape taken out, leaving only the skins to represent the 
air-cells. Suppose the stems to be hollow, and they will 
represent the air-tubes. Now, put several such bunches 
together, so that the main stems all join in one large 
stem, and you have something which represents the air- 
cells and air-tubes of a lung. To make it complete, sup- 
pose all the grapes to be joined by fine threads, like a 
spider's web. This represents the fibrous tissue, which is 
quite elastic. Suppose a blue tube to run along the main 
stem, and divide every time the stem does, until its small 
branches finally reach every grape, and form a net-work 
on it. From that net-work suppose red tubes to run 



126 



THE HUMAN BODY. 



back by the sides of the blue ones, joining, constantly, 
other tubes, until all are united in two large ones on the 
main stem of our bunches of grapes. The blue tubes are 
the pulmonary artery and its branches. The net-works 
on the grapes are the capillaries, and the red tubes are 
the pulmonary veins. 



Bronchial 
tubes. 



Larynx. 




Fig. 49. 
Section of the Lungs, partly showing the Course of the Bronchial Tubes. 

In such a figure we have the air-tubes and air-cells: we 
have the blood-vessels, and we have the fibrous tissue. If 
we add the lymphatic vessels and nerves, we have all that 
makes up the lung. 



RESPIRATION AND THE VOICE. 127 

7. A tree is another illustration of a lung. The trunk 
represents the bronchus, or great air-tube, which enters 
the lung. The branches represent the small (bronchial) 
tubes. The leaves represent the air-cells. If we suppose 
tubes to be laid along the trunk and branches, constantly 
dividing, until finally each leaf is covered with a net- 
work from which other tubes come off, and run back 
toward the trunk, uniting as they go, we shall have 
again something like a lung, with the fibrous tissue, 
the nerves, and lymphatic vessels and glands, still to be 
added. 

8. Do not suppose, however, that, on examining a lung, 
you would see all these tubes and cells. On the contrary, 
you would see only a light-gray or pinkish substance, 
mottled with black spots, very smooth on the outside. If 
you were to cut into it, it would look a little like fat. 
The cells, and many of the tubes, are so. small, that only 
very careful study with the microscope has given us our 
knowledge of them. 

THE AIR-PASSAGES. 

Section III. — 1. The passages by which the air gets 
to the lungs, are, — 

The nose, The larynx, ),.,.. 

The mouth, The trachea, j (windpipe). 

The throat, The bronchi. 

2. The nose is the true breathing passage. It consists 
of two parts: — 

1. The triangular projection from the face. This is 
partly cartilage, which is flexible, and partly bone. 

2. The cavities behind, called the nasal fossse. There 
are two of these, corresponding to the two nostrils, sepa- 



128 



THE HUMAN BODY. 




Fig. 50. 

Section of Nasal Fossae, seen from 

Behind. 



rated by a partition. They are narrow, but quite exten- 
sive. They enter into the upper part of the throat by 
two openings, like the two on the face. Above, they con- 
nect with cavities in the 
forehead, and at the sides 
with cavities in the upper 
jaw-bones, and wath the 
eye. These passages and 
cavities are lined with 
mucous membrane; and 
when this is inflamed, as 
in a cold in the head, we 
have a feeling of fullness, 
not only in the nose, but 
also in the forehead and 
eyes. 

3. The nerves jof smell are up in the top of the nasal 
cavities. In ordinary breathing, the air passes straight 
back to the throat; but, when we wish to smell any 
thing distinctly, we sniff suddenly, and so draw the air 
up to the top of the cavities, with the odorous particles 
in it. 

4. The odorous particles will diffuse themselves through 
the cavities, and reach the nerves, without this sniffing, 
unless they are few and faint. But, by sniffing the air, 
we get the sensation more quickly and keenly. 

5. A horse can not breathe through his mouth, but a 
man can. We do so when the nose is stopped, and when 
we are breathing rapidly, as in exercise. Some always 
do so when asleep. 

It is better to breathe through the nose, because, — 
l. The nasal cavities being narrow, the air is spread out 



RESPIRATION AND THE VOICE. 129 

in a thin sheet, and so is warmed by the warm walls of 
the cavities. It passes through the mouth in a large 
stream, and pours into the lungs without being properly 
warmed in cold weather. 

2. Dry air, passing through the nasal cavities, is not only 
warmed, but moistened. When it is taken through the 
mouth, it dries the throat, as any one can learn by trying 
it rapidly for a few moments. Hence, the practice tends 
to produce sore-throat. 

$. Snoring is a result of sleeping with the mouth open. 
The soft palate, which hangs like a curtain between the 
passages from the nose and the mouth, is relaxed in sleep. 
The two currents of air, one on each side of it, cause it to 
vibrate rapidly, just as a sheet will flap and rattle in the 
wind. 

6. The habit of breathing through the nose, both in 
waking and sleeping hours, should, therefore, be culti- 
vated. One of the best safeguards against catching cold in 
the throat, on going from a heated room into the night 
air, is to keep the mouth shut. 

7. The throat is both a food-passage and an air-passage. 
Air is sometimes swallowed into the stomach : food and 
drink sometimes enter the wind-pipe; but, if they do, there 
is a great disturbance, and they must be coughed out at 
once. Commonly, each takes its proper course,- — the food 
through the gullet, the air through the wind-pipe, and that 
without any thought on our part, The apparatus is self- 
regulating. When we swallow, the breathing-passage 
closes up tight; and a kind of trap-door, called the epi- 
glottis, shuts down over it. You can not swallow and 
breathe at the same time. 

8. The larynx, which is the upper part of the wind- 



130 THE HUMAN BODY. 

pipe, is a kind of a box made of cartilage. It is wider 
than the rest of the wind-pipe, and projects in front, 
making Adam's apple. It is the voice-box. In it are 
the vocal cords, or bands, by which sound is made. It 
will be more fully described hereafter. 

9. The trachea is a tube four or five inches long, and 
from half an inch to an inch in diameter, extending from 
the larynx down into the chest. It is made of a series of 
flat rings of cartilage, sixteen or twenty in number, which 
do not quite come together behind, but are somewhat like 
a horseshoe. These are connected, and covered with mem- 
brane and muscular fibers. They serve to keep the tube 
open. 

10. The trachea divides into two branches, called bron- 
chi. One goes to the right, and one to the left, lung. 
They are made just like the trachea, and are one or two 
inches long. 

11. Each bronchus, as it enters the lung, divides into 
smaller tubes, called bronchial tubes; and these keep on 
dividing until they are not more than t -J-q of an inch in 
diameter. They then end in the air-cells. 

BREATHING. 

Section IV. — 1. We have studied the lungs, and the 
passages leading to them. We have now to study the 
process by which air goes in and out of them. It is not 
enough that the passage is open. The lungs are not like 
a house, with windows and doors, through which the 
breeze plays freely. They are, rather, like a deep well, 
or a mine, into which fresh air will not go, unless, in 
some way, a current is made. We make this current by 
breathing. 



RESPIRATION AND THE VOICE. 



131 



2. If you watch the breathing, you will see two regular 
movements. First, the chest and abdomen seem to swell ; 
and then, in a moment, they fall back to their former 
size. This is repeated with every breath. The chest does 
enlarge; and, as it enlarges, the air rushes in, to fill the 
extra space. As it grows smaller, the same amount of air 
that entered is squeezed out again. 

Why does the air rush in, when the space is made 
larger? Because air is like 
water : it is pressing in every 
direction. If you put water 
in a tub with a pipe opening 
out of it, it will force itself 
into the pipe. If you put 
a bottle under water, with 
the mouth up, the water will 
push in, and fill it. We are 
in the air as the bottle is in 
the water. If the bottle is 
made of rubber, the water will 
flow out when we squeeze it, 
and will flow in again when 
it expands. The chest may 
be likened to such a rubber 
bottle. 

The chest is like a bellows, with one exception : in a 
bellows, the air enters by one opening, and goes out of 
another ; in the chest, air enters and goes out by the same 
opening. 

3. How is the chest made larger? In two ways, — 

1. By the descent of the diaphragm. 

2. By the raising of the ribs and breast-bone. 




Fig. 51. 
The Chest. 



132 THE HUMAN BODY. 

The diaphragm is attached to the lower edge of the 
walls of the chest, and stretches across, separating chest 
from abdomen, forming the floor of one and the roof of 
the other. But it is not a flat floor. It arches up into the 
chest, as may be seen in the figure, and is supported in 
this position by the contents of the abdomen beneath it. 
When we take a breath, the diaphragm contracts, — 
being partly muscle, — and the top of the arch is flattened, 
making more room in the chest. At the same time, the 
contents of the abdomen are pressed down, and the walls 
of that cavity expand to accommodate them. The ab- 
domen is not made larger when we take breath. It ex- 
pands in front just enough to make up for what it loses 
by the flattening of its roof. 

4. But the chest is enlarged, not only by the descent of 
its floor, but also by the raising of the ribs and breast- 
bone. The ribs are joined to the backbone behind, and 
connected with the breast-bone by the costal cartilages, 
which will bend. To the ribs are attached muscles which 
pull them up, and others which pull them down. ■ The 
former are called inspiratory muscles, and the latter expir- 
atory muscles. Now, clasp your hands, and extend your 
arms in front of you, slanting a little downward. Your 
hands represent a portion of the breast-bone, and your 
arms two of the ribs. Keeping your hands clasped, raise 
your elbows as much as you can, and raise your hands a 
little. That is the motion that the inspiratory muscles 
give to the ribs and breast-bone. You can see that the 
space included between them is enlarged in both direc- 
tions. 

5. We have been speaking of the cavity of the chest. 
The air enters the lungs. But the lungs occupy almost 



RESPIRATION AND THE VOICE. 133 

all of the chest, except the space filled by the heart. 
They are attached to its walls and floor. They are elas- 
tic ; and so, when the chest enlarges, the lungs enlarge 
with it, and the air-cells open wide. When the chest 
sinks back to its former size, the elastic lung shrinks too ; 
and the air is driven out. 

6. The lungs are held to the chest-wall by the pleuras. 
These are two empty, air-tight sacs, one for each lung. 
One layer covers the lung; and the other lines the chest- 
wall, and is attached to it. The insides of these two 
sacs are moistened by a fluid, so that there is no friction 
between the lung and the chest : and, as the sacs are air- 
tight, the layers can not be separated ; and the chest-wall, 
in its movements, pulls the lung with it, just as the circle 
of wet leather, which the boys call a sucker, lifts a stone. 
The pleura is like the inner portion of the pericardium. 

7. To recapitulate briefly. The lungs, consisting largely 
of little air-cells, with the air-tubes leading to them, are 
elastic. They nearly fill the chest, and cling closely to 
its walls and floor. When the chest expands by the de- 
scent of its floor and the ascent of its walls, the lungs 
expand with it. The air-cells open, and the outside air is 
pushed in to fill them, — as the air enters a bellows when 
we separate its walls. When the inspiratory muscles stop 
pulling, the chest settles back to its former size, the expi- 
ratory muscles helping it a little, and sometimes a good 
deal. 

8. We breathe without thinking of it in sleep as well 
as when awake. We can not refrain from it for many 
seconds. Constant breathing is necessary to life, so it 
must be independent of our wills. 



134 THE HUMAN BODY 



CHANGES IN THE BLOOD. 

Section V. — 1. Part of the oxygen of each breath 
taken in, after reaching the air-cells, goes through their 
walls, and through the walls of the capillaries outside of 
them, into the blood. It joins itself to the red corpuscles ; 
and they float on with it through the heart, and out into 
the aorta, and finally into the capillaries of all parts of the 
body: there it leaves the corpuscles, drawn by a more 
powerful attraction through the capillary walls, to help 
to nourish and build up the surrounding substance. 

2. The blood, as it discharges its load of oxygen from 
the capillaries, takes up, at the same place, a new load 
of carbonic-acid gas. The oxygen is the nourishment for 
the tissues, — the fuel for the fire; and the carbonic-acid 
gas is like the ash, which must be removed, or else the fire 
will be clogged. As the blood thus changes its load, a 
marked change in its color takes place. As it comes from 
the lungs, it is scarlet, and so continues through the heart 
and arteries until it reaches the capillaries : there it turns 
blue, and so continues through the veins and the heart 
and the pulmonary artery until it reaches the lungs 
again. 

In the capillaries of the larger, or systemic, circulation, 
the blood turns blue. 

In the capillaries of the lesser, or pulmonary, circulation, 
the blood turns scarlet. 

3. We know that it is the oxygen taken in by the lungs 
that gives blood its scarlet color, and that it is the loss of 
oxygen in the tissues that makes it turn blue. For if we 
take some blue blood from a vein, and shake it up in the 
air, it will turn scarlet ; and the color will be the same 



RESPIRATION AND THE VOICE. 135 

when it contains much carbonic-acid gas as when it con- 
tains little. 

4. The blood is the common carrier of the nutriment 
that we get from food and air ; and it takes away, not only 
carbonic-acid gas, but all other waste matters. Some it 
discharges by the kidneys, some by the skin; the car- 
bonic-acid gas, chiefly by the lungs. 

WASTE MATTERS GIVEN OFF BY THE LUNGS. -CHANGES 
IN THE AIR. -VENTILATION. 

Section VI. — 1. The lungs, therefore, serve not only 
to take in oxygen, but also to discharge carbonic-acid gas, 
w T hich is one of the chief waste products of the body. 

Another product of the waste of the body, which is dis- 
charged by the lungs, is water. This ordinarily passes 
off in the breath as invisible vapor. But in very cold 
weather it is condensed as it comes out, and we can see 
it. It lodges and freezes on the beards of men, and on 
the hair of animals. If the vapor in the breath of a man 
is collected for twenty -four hours, and condensed to w T ater, 
it measures as much as a pint. 

2. The breath of man, and of every animal, when 
breathed out, contains, besides carbonic-acid gas and 
water, a very little of a certain substance which gives to 
each its peculiar odor. The breath of a cow, for ex- 
ample, has a smell peculiar to the animal. In pure, 
fresh human breath, we do not recognize any odor; but 
the substance is present: and in ill-ventilated rooms, 
where many people have been breathing, it becomes 
changed, and makes the air offensive and unhealthy. 
These three substances — oxygen, carbonic-acid gas, and 
an unnamed animal substance — are always present in 



136 THE HUMAN BODY. 

the breath. Other matters which give a distinct smell 
are often found in it, but not constantly. 

3. The amount of air in a single breath is about twenty 
cubic inches, which would be a globe of air a little smaller 
than a base-ball. We take about eighteen breaths in a 
minute; in an hour, we breathe about twelve cubic feet of 
air; and in a day, about three hundred. Since we breathe 
more than eighteen times in a minute when we are exer- 
cising actively, probably three hundred and fifty feet 
would be nearer the amount used in a day. This would 
equal the entire contents of a room between seven and 
eight feet on every side. 

4. Every breath, as it comes from the mouth, is changed 
in four ways, — 

1. It has lost oxygen. 

2. It has gained carbonic-acid gas. 

3. It has gained watery vapor. 

4- It has gained a nameless animal substance. 

This breath is not fit to be breathed again. To be sure, 
there is still oxygen in it, but not so much as in fresh air. 
The loss of even one of the twenty-one parts in a hundred 
of oxygen, which fresh air contains, makes air less sup- 
porting; and if eleven parts are lost, though there are still 
ten parts left, we could not live in it. Moreover, the 
carbonic-acid gas has an injurious effect. 

5. The stream of air which we pour out at each breath 
does not remain distinct, but mixes immediate^ with the 
surrounding air, just as a glass of colored fluid, if poured 
into a pail of water, will quickly diffuse itself through the 
whole. We never breathe precisely the same breath a 
second time, and the air of a room only very gradually 
becomes bad when many people are breathing in it. In 



RESPIRATION AND THE VOICE. 137 

a large room, such as a church, many people can remain 
for a long time without suffering, even if the air is not 
changed. They may not be aware that it is growing im- 
pure, though one coming in from out of doors would know 
it at once. If the room is small, the air must be constantly 
changed, or they will be distressed. 

6. The Black Hole, at Calcutta, was a room in which 
one hundred and forty -six men were confined over night. 
It was eighteen feet square, and had two small windows, 
through which the air did not come freely. Their suffer- 
ings were intense, and only twenty-three of them were 
alive in the morning. 

7. Nothing is so free and abundant as fresh air; and yet 
we all suffer frequently, and many suffer constantly, for 
want of it, We should always remember its importance. 
It is possible to become accustomed to close rooms. We 
may not know what is the cause of a drowsy head, a disin- 
clination to exercise, and general ill health, while it is 
simply lack of fresh air. Sleeping-rooms, in which we 
spend a third of every day, unconscious of the state of 
the air, should be well ventilated. 

8. It is very difficult to get fresh air enough into our 
dwellings and public buildings, and, at the same time, to 
avoid draughts, and keep warm. Ventilation is almost a 
science by itself. There are many ways, but no one way 
which will do for every room. But if we all bear in mind 
the necessity of fresh air, and use our judgment and 
ingenuity, we shall get it. 

THE VOICE. 

Section VII. — 1. The organs of breathing are, at the 
same time, organs of voice. The larynx is especially the 



138 



THE HUMAN BODY. 



voice-box ; but the lungs, the bronchial tubes, the trachea, 
and the throat, mouth, and nose, all have a part in mak- 
ing and forming sounds. 

2. The toy pipes, which have, near the mouth-piece, 
narrow bands of brass, between which the air passes, and 

which make a reedy sound, are some- 
what like the organ of voice. The 
chest and lungs give the wind, the 
trachea is the pipe, the larynx contains 
the vocal cords, which make the sound. 
The larynx is divided in two parts by 
a membranous partition, which has a 
slit in it, running forward and back- 
ward. This slit may be opened or 
shut, or made longer or shorter, by the 
action of many little muscles, which 
surround it. 

The edges of this slit, which is called 
the glottis, are the vocal cords. Every 
breath has to pass through it; but, 
in ordinary breathing, no sound is 
produced. If we wish to make a sound, the little mus- 
cles tighten up the cords, and make the slit narrow ; and, 
as the lungs are squeezed in the chest, the air forced out 
through the slit makes the cords vibrate. This makes 
the sound. We shape this sound by changes in our 
throats and mouths. 

3. A reed-organ is somewhat like the vocal apparatus ; 
but, in the instrument, there is a pipe for every note. The 
windpipe can be so varied in length and in size, and the 
voice-box, with its cords, can be so changed in many ways, 
that a single pipe can make many different sounds. 




Fig. 52. 
The Larynx. — 1. Adam's 
Apple. 2. Trachea. 



RESPIRATION AND THE VOICE. 139 

4. The voice can be improved by cultivation. The 
breathing-muscles grow stronger, and also the muscles of 
the voice-box itself. The power to make firm, clear, sweet 
sounds increases. It is by singing that this is sought. But 
singing is not the only way of improving the vocal powers. 
To speak well is of more consequence than to sing well. 
In singing, the sound is the main thing, and less attention 
is paid to articulation. In speaking, it is important, not 
only that the tones should be clear and pleasing, but also 
that the pronunciation of words and syllables and letters 
should be distinct and correct. By taking care in speak- 
ing, we gradually train the muscles of the tongue and 
cheeks and throat, by which we make words, until it be- 
comes a habit to speak well. 



QUESTIONS. 

Section I. — 1. What is respiration? 
2. What would air look like if we could see it? 
• 3, Is air a material substance? What is it composed of? 

4. What is the use of the nitrogen in the air? 

5. What is the use of carbonic-acid gas in the air? Does man 
use it? What is adding constantly to the carbonic-acid gas in the 
air? What is adding constantly to the oxygen in the air? 

6. Name some characteristics of oxygen. 

Section II. — 1. Does all of the air which we breathe in enter the 
blood? 

2. What are the lungs ? How does the oxygen pass through them 
into the blood-vessels ? 

3. How do frogs breathe under water? 

4. How do fishes breathe? 

5. In what are all breathing organs alike ? 

6. Illustrate the structure of a human lung by a bunch of grapes. 



140 THE HUMAN BODY. 

7. Illustrate the structure of a lung by a tree. 

8. Can this structure be seen with the naked eye? 

Section III. — 1. Name the passages by which the air reaches 
the lungs. 

2. What two parts does the nose consist of? With what other 
cavities are the cavities of the nose connected? 

3, 4. Where are the nerves of smell, and how do the odorous 
particles reach them? 

5. Give three reasons for breathing through the nose rather than 
the mouth. 

6. What is a safeguard against taking cold when going from a 
heated room into cold air? 

7. Where do the air-passage and the food-passage cross each 
other? Why does not food enter the windpipe? 

8. What is the larynx? 

9. Describe the trachea. 

10. Into what does the trachea divide? 

11. Describe the course and termination of the bronchial tubes. 

Section IV. — 1. Does air enter the lungs of itself ? 

2. What movements can we see when we watch a person breath- 
ing? What change takes place in the chest? Why does the air 
enter it? What is the chest like? 

3. In what two ways is the chest made larger? Describe the first- 
named way. 

4. Describe the second-named way. 

5. Why do the lungs enlarge when the chest does? 

6. What are the pleurse? 

7. Describe briefly the process of breathing. 

8. Does the will have any thing to do with ordinary breathing? 

Section V. — 1. Follow the course of oxygen as it enters the 
blood. 

2. What change in the color of the blood takes place? Where 
does the change from red to blue take place? Where does the 
change from blue to red take place? 

3. What is the cause of the change in color? 

4. What is the work of the blood ? 



RESPIRATION AND THE VOICE. 141 

Section VI. — 1> 2, What do the lungs do besides taking in 
oxygen? What waste products are discharged by the lungs? 

3. How much air is there in a breath ? How much air do we 
breathe in a day? 

4. What four changes take place in every breath ? Has it lost all 
its oxygen? How much oxygen must air contain to support life? 
How small a loss of oxygen will be felt ? 

5. Do we breathe the same air a second time ? 

7. What are the immediate effects of lack of fresh air? 

8. How should we try to secure fresh air ? 

Section VII. — 1. What are the organs of voice? 

2. How are the organs of voice like a reed-pipe? and what part 
does each do? What is the glottis? What are the vocal cords? 

3. W T hat resemblance between the vocal organs and a reed-organ? 

4. How should the voice be cultivated ? 



142 



THE HUMAN BODY, 



Cerebrum. 
Cerebellum. 




Fig. 53. 
General Representation op the Nervous System. 



THE NERVOUS SYSTEM. 143 



CHAPTER IX. 
THE NERVOUS SYSTEM. 

Section I. — 1. An injury to the head, if violent 
enough, will kill at once. If less violent, it will stun the 
victim. He will drop, limp and helpless, and will know 
nothing for a time; but his heart will continue to beat 
feebly, and he will still breathe. In time he will get his 
senses, and his power over his muscles again. 

2. An injury to the backbone, if violent enough, will 
paralyze the lower limbs. The man is not stunned ; and 
he breathes, and his heart beats. He can move with all 
the muscles above the injury: but those below are useless, 
though they have not been hurt ; and perhaps he will have 
no feeling in those parts. In the case of the injury on 
the head, the part that is hurt is the brain. In the case 
of the injury on the back, the part that is hurt is the 
spinal cord. 

3. The brain fills the chief cavity of the skull. It is 
not one mass, but several masses joined together. The 
largest mass is called the cerebrum. The next in size is 
the cerebellum (little brain), which lies behind and beneath 
the cerebrum. The pons Varolii is a mass in front of the 
cerebellum and beneath the cerebrum. The medulla 
oblongata is beneath the cerebellum, and behind the pons 
Varolii. 

Suggestion to Teachers. — Section I. 3. Get a sheep's or calfs brain. 
The chief divisions, the convolutions, and the gray and white matter, can be 
shown. 



144 



THE HUMAN BODY. 



4. Each of these masses is in two halves, which are 
precisely alike. The two halves of the cerebrum and cere- 
bellum are partly separate. The two halves of the pons 
and the medulla are united. 

5. The surface of the cerebrum and cerebellum, instead 
of being smooth, is divided into ridges, with furrows be- 
tween them. These ridges are called the convolutions of 




Fig. 54. 
Half of the Brain and Upper End of the Spinal Cord, with the Nerves 
coming from them. — 1. Cerebrum. 2. Cerebellum. 3. Pons Varolii. 4. Medulla 
oblongata. 5. The Eyeball. 

the brain. One great difference between the brain of man 
and of the lower animals is, that it has more of these 
convolutions. Very intelligent animals have more of 
them than animals less intelligent. 

6. The medulla oblongata is the lowest portion of the 
brain. It is just above the great opening in the base of 
the skull. Through that opening, it is continuous with 
the spinal cord. 



THE NERVOUS SYSTEM. 



145 



C 
O 
W 




mm& 






7. The spinal cord occupies the spinal canal in the 
backbone. It is about half an inch thick, and eighteen 
inches long. Before reaching the 

lower end of the canal, it divides > 
into a bunch of fine cords, which 
make the cauda equina (horse's 
tail). 

The spinal cord, like the brain, 
is partly divided, lengthwise, into 
tw r o halves, which are alike. 

8. Both the brain and spinal 
cord have three coverings wrapped 
around them, called the membranes 
of the brain and cord. 

From each half of the brain 
tw r elve small cords come off, and 
go out through holes in the skull. 
From each half of the spinal cord 
thirty-three small cords come off, | 4/I1LJ? 

by two roots each, and go out of 
the spinal canal through openings 
between the vertebra. These are 
the nerves. 

9. The substance of the brain 
and cord is soft and cheese-like. 
It is of two colors, white and gray. 
The whole surface of the cerebrum and cerebellum, about 
a quarter of an inch deep, is gray. The deep parts of both 
are chiefly whita In the cord, it is different. The deep 
part is gray, and the surface is white. 

10. A blow on that part of the elbow called the "funny- 
bone," gives a tingling sensation all the way down to the 
little finger. 



146 



THE HUMAN BODY. 



If we should cut into the elbow to find the " funny- 
bone/' we would come upon a flat, shining cord about an 
eighth of an inch wide. If we should follow this cord 
down, we would find it divide into smaller cords; and, if 
we should follow each one of these, we would see it finally 
ending in the muscles, or in the skin, or some other tissue, 
in a great many fibers, so fine that only a microscope 
would show them. Many of them go to the little finger, 
where the tingling is most felt. If we should search 
farther for such cords, we would find that they were in 
nearly every part. We would find that some of them 
were as large as the one first seen, but that the smallest 
were smaller than the capillary blood-vessels, and as 
numerous. 

11. If, starting from the elbow, we should follow the 
cord first found up the arm, we would see it joining other 
cords, and perhaps itself dividing ; and finally we would 
trace it through one or more of the openings between the 

vertebrae (intervertebral fora- 
mina) into the spinal cord. 

If we followed any other 
cord up, it would lead us 
finally into the spinal cord 
or the brain. Most of these 
white cords, which are the 
nerves, have one end divided 
if into the finest of fibers in 
the different parts of the 
body, and the other end in 
the spinal cord or brain. 
The brain and spinal cord are called the nerve centers. 

12. By examination with the microscope, it is found 




Fig. 56. 

Nerve-cells (Magnified). 



THE NERVOUS SYSTEM. 



147 



that the gray part of the brain and spinal cord is partly 
made of cells of various shapes, with fibers running out 
of them. The white matter is made of nerve fibers lying 
side by side. The nerves consist entirely of white nerve 
fibers. Most of the gray matter with its cells is found 
in the nerve centers. 

ACTION OP THE NERVOUS 
SYSTEM. 

Section II. — 1. If 
nerves are cut off, we shall 
find a great change in 
the parts to which they 
go. If all the nerves 
going to a particular part 
of the skin are cut off, 
that part of the skin will 
be insensible. You may 
prick or pinch it, and it 
will not feel. If all the 
nerves going to a muscle 
are cut off, that muscle 
will not obey your will: 
you can no longer use it. 

2. What you have done 
has not injured directly 
the skin or the muscle. 
It has cut off their con- 
nection with the nerve 
centers. We infer, therefore, that it is not really the 
skin that feels when we prick it. It is something in 
the nerve centers, and the nerve is the road by which the 




Fig, 57. 
Nerves op the Shoulder and Arm. — 
1. Artery. 2. Nerves. 



148 



THE HUMAN BOUY. 



effect of the prick gets to the centers. When that road is 
cut off, we feel nothing. We infer, also, that the muscle 

does not commonly move of itself. 
It is caused to move by something 
in the nerve centers, and the nerve 
is the road by which the influence 
from the center that makes it move 
gets to it. 

3. The nervous system may be 
compared to the telegraphic sys- 
tem of a railroad. The nerves are 
the wires. The gray matter of the 
spinal cord contains the offices of 
the district superintendents. In 
the cerebrum is the office of the 
superintendent of the road. Sup- 
pose a mosquito lights on your face, 
and puts in his bill. He can not 
put it in, small as it is, without hit- 
ting one or more little nerve fibers. 
Instantly a message goes along 
those nerve fibers, through the 
nerve-trunks, through the spinal 
cord, and finally to the general 
superintendent's office. The mes- 
sage is, "Something wrong here/ 7 
Immediately an order is sent out, 
along other nerve trunks and fibers, to the muscles of the 
shoulder and arm ; and they contract, so as to strike the 
mosquito. 

4. This is done very quickly, and yet it takes some time. 
The message goes in at the rate of one hundred and forty 




Fig. 58. 
Nerves of the Fore-arm and 
Hand. — 1. Artery. 2. Nerves. 



THE NERVOUS SYSTEM. 149 

feet in a second ; it goes out at the rate of about ninety feet 
in a second; and it takes a little time for the superintend- 
ent to receive the message, and give the order. Then it 
takes time for the muscles to contract. 

If the mosquito is quick, he will escape you. 

REFLEX ACTION. 

5. In the night, the general superintendent's office is 
ctosed : the cerebrum is asleep. And yet, if the foot is 
pricked or tickled, it will be drawn up. A frog's brain 
may be taken out entirely, without killing him. If then 
his side is pricked, he will scratch it with his foot. This 
shows us that the general superintendent in the cerebrum 
does not do all the regulating of the body. There are 
district superintendents in the spinal cord, and in the 
medulla ; and some matters are never sent up to the cen- 
tral office at all. Digestion and respiration and circula- 
tion are all regulated by district superintendents. 

6. Such actions are called reflex actions; because the 
message is sent in, and the order for the act " reflected" 
back, without any action of the will. 

Winking is ordinarily a reflex act. The eye gets a 
little dry. The message goes in along the nerve fibers, 
which end just beneath its surface ; and the order comes 
out to a muscle which brings the lids together, and spreads 
moisture over the eye. 

Coughing is a reflex act. Something tickles the throat, 
or the air-passages below; and we can not help coughing. 
The muscles of expiration combine to throw r out the thing 
that tickles. 

Sneezing is a reflex act, for the purpose of clearing the 
air-passages above the throat. All these acts are regulated 
by centers below the cerebrum. 



150 THE HUMAN BODY. 

7. Many actions which must, at first, be attended to by 
the cerebrum, may, after a time, be handed over to the 
offices lower down. For example, in learning to play on 
the piano, it is necessary, at first, to give the whole mind 
to every touch. After a while, difficult music can be 
played with little thought. 

If we were not made so that we could act in this way, 
our whole time and attention would be taken up in doing 
the things which now seem the simplest. Our minds would 
be worn out in making the movements, and combinations 
of movements, necessary in eating and breathing and 
walking. 

8. The nerve-fibers which carry messages in to the 
centers are called sensory fibers. The nerve fibers which 
carry messages out to the muscles are called motor fibers. 

9. The messages do not all come from the outside, as in 
the case of the mosquito-bite. A wish or thought may 
start in the cerebrum, without any impression from out- 
side, and cause an order to be sent out to the muscles. 

10. The nervous system connects the different parts of 
the body, and makes them work together. 

THE CEREBRUM THE SEAT OF THE HIGHER FACULTIES. 

Section III. — 1. We have taken it for granted, that 
the cerebrum is the seat of the higher faculties, — the 
memory, the reason, the will, the feelings. This is proved 
in two ways : — 

1. If this portion of the brain be diseased or injured, 
these faculties are affected. 

2. The more of the higher faculties an animal has, the 
larger is the cerebrum in proportion to the rest of the 
brain. Man has the largest cerebrum proportionally. 



THE NERVOUS SYSTEM. 151 

Section IV. — 1. We say that a person is nervous when 
his nervous system is excited by trifling matters. Sick- 
ness makes people nervous. Close rooms and bad air make 
people nervous. Lack of exercise makes people nervous. 
Indigestible food makes people nervous. The nervous 
system will endure a great deal of wear if rightly treated. 
Lack of sleep, too much excitement, and anxiety, often 
break it down. Worry is much more wearing than 
work. Stimulants, which spur the nerves continually, 
finally prostrate them. 

2. Actions at first done with care and thought, by being 
done frequently, are at length done without effort. They 
become partly reflex acts. That is the reason why a 
skilled workman can work so much longer without being 
tired than a stronger man could, who was not so skill- 
ful. In this way good habits help us, — good habits of 
position, of movement, of speech, of study. So bad habits 
make slaves of us. The habit of biting the nails is, in 
many persons, a reflex act, which it is difficult to refrain 
from, because it is done without thought. 

3. The brain needs exercise just as truly as the muscles. 
Study and thought not only make the brain strong and 
clear: they help to keep it in good health. 

EFFECTS OF ALCOHOL ON THE NERVOUS SYSTEM. 

Section V. — 1. Alcoholic drinks are used chiefly for 
their effects on the nerves and brain. They stimulate the 
sense of taste in the tongue and palate, and they warm the 
stomach. Without really increasing strength, they give a 
feeling of strength and confidence. In moderate doses, 
they excite the brain. The sensibilities become lively, 
ideas flow readily, wit seems brighter, and philosophy 



152 THE HUMAN BODY. 

more profound. The nerves that control the muscles are 
but little affected at this stage, and yet they are disturbed. 
A very little wine may spoil the chances of a rifleman in 
a shooting-match, or of a player in a game of ball. 

2. As the amount of alcohol is increased, the higher 
faculties of the mind grow dull, while the lower propensi- 
ties are still further excited. That portion of the brain 
which presides over the muscles loses its control. They 
still act with force ; but they have no guide, and they do 
not act together. A drunken man can strike a hard blow, 
but he can not hit straight. The muscles of his legs fail 
to combine their action. They are all at cross-purposes, 
each contracting and relaxing without the direction of a 
central power. The man's movements become as tangled 
as his thoughts. 

3. Vanity and pugnacity are now aroused; recklessness 
displaces caution; finally all self-control is lost, and the 
lowest instincts rule. Ungoverned impulses lead to crime 
and violence. The final stage is the drunken sleep. 

The course of events varies with different temperaments. 
Some are but little excited, but gradually become stupid ; 
some never lose control of their limbs; some are good- 
natured; and some uniformly morose. All are for the 
time insane. 

4. The after-effects of free indulgence in alcoholic drinks 
are, an aching head, a foul stomach, unsteady nerves, and 
depression of spirits. 

Drinkers often reach a condition in w T hich this depres- 
sion is constant, except when they are under the influence 
of liquor. 

The appetite in many cases grows by gratification. It 
becomes so strong that it is almost impossible to resist it: 



THE NERVOUS SYSTEM. 153 

conscience is powerless; ambition, pride, and self-respect 
are abandoned. The most sacred affections are trampled 
under foot to satisfy the thirst, This condition is disease, 
but it is a disease for which the victim is himself re- 
sponsible. 

5. One of the most marked effects of alcohol is an en- 
largement of the small blood-vessels. This is what makes 
a toper's face red. Not only in the face, but in other 
parts, this enlargement takes place. Alcohol does it by 
paralyzing the little nerves, which are the regulators of 
the size of the vessels. These nerves constitute a very 
delicate mechanism of Nature's contriving, and it is im- 
portant to the health of the body that it should not be 
interfered with. 

6. Alcohol taken into the stomach is rapidly diffused 
through the body by the blood. Various experiments 
have proved that it accumulates especially in the brain. 
In this delicate organ, it causes not only the temporary 
effects already described, but permanent changes which 
manifest themselves in various diseases. Among them 
are epilepsy, paralysis, and insanity. 

SUMMARY OF THE ACTION OF ALCOHOL ON THE BRAIN 
AND NERVES. 

7. l. It first excites, and then paralyzes. 

2. The higher faculties are the first to be paralyzed, 
leaving the man under control of his lower passions. 

3. It obscures the senses, and impairs the judgment, 

4. It exhausts the whole nervous system, and leads to 
paralysis, epilepsy, and insanity. 



154 THE HUMAN BODY. 



QUESTIONS. 

Section I. — 1. What may be the effects of injury to the head? 

2. What may be the effect of an injury to the back? 

3. Of what parts does the brain consist ? 

5. What are the convolutions of the brain? How do these indi- 
cate the difference between man and the lower animals ? 

6. 7. Describe the spinal cord. 

8. What are the membranes of the brain and cord ? How many 
nerves come from the brain ? How many from the spinal cord ? 

9. What is the appearance of the brain substance? What is the 
appearance of the substance of the spinal cord? 

10. Why does a blow on the funny-bone cause a tingling in the 
little finger? 

11. What is the course of the nerves outward? What is the 
course of the nerves inward? What are the nerve centers? 

12. What does the microscope show of the structure of the gray 
matter? Of the white matter? 

Section IT. — 1. What is the effect of cutting off the nerve-sup- 
ply of a portion of the skin ? Of a muscle ? 

2. What do we infer from this effect? 

3. Compare the nervous system to a railroad telegraph. What 
takes place when a mosquito stings ? 

4. Does it take time for a sensation to go through the nerves, or 
for a motor impulse to return? Do they go as fast as electricity? 

5. 6, What are reflex actions ? Name and describe some such 
actions. 

7. May acts at first done by the cerebrum become reflex acts ? 

8. What are the sensory fibers? What are the motor nerve 
fibers ? 

10. How does the nervous system connect the different parts of 
the body ? 

Section III. — 1. How do we know that the cerebrum is the seat 
of the higher faculties ? 

Section IV. — 1. What is it to be nervous ? What makes people 
nervous? What breaks down the nervous system? 



THE NERVOUS SYSTEM. 155 

2. How do good habits help us? 

3. Does the brain need exercise? 

Section V. — 1. For what chiefly are alcoholic drinks used? Do 
they increase strength? What is their first effect in moderate 
amount? 

2, 3. What is the effect if drinking continues ? Are all affected 
in the same way by alcohol ? 

4. What are the after-effects of free drinking? Is the appetite 
easily controlled ? 

5. How does alcohol make a toper's face red ? 

6. For what part of the body has alcohol a special affinity? 
What diseases of the brain are among its effects ? 

7. Give a summary of the effect of alcohol on the brain and 
nerves. 



156 THE HUMAN BODY. 



CHAPTER X. 
THE SKIN. 

STRUCTURE OF THE SKIN. 

Section I. — 1, The skin is the covering of the body. 
It is soft and smooth, but strong. It fits perfectly ; but it 
stretches and glides a little on the muscles beneath, and, 
therefore, does not hinder our movements, as close-fitting 
garments do. It is partly transparent, and shows the 
blue color of the veins, and the red of the arteries, beneath 
it. 

It becomes quite thick in places where a thick covering 
is needed, as on the palms of a laboring-man, or the soles 
of a barefoot boy. 

2. If we prick a blister, a little watery fluid comes out, 
and it flattens down. It does not hurt to prick it, and it 
draws no blood. So we find that the top layer of the skin 
has no nerves or blood-vessels. But, when we " scrape the 
skin off," we are hurt, and have a red, bleeding surface. 
We do not often really scrape the skin off with trifling ac- 
cidents; but we take off the top layer, and get down to the 
deep layer, which contains both nerves and blood-vessels. 

3. Dandruff, which comes from the scalp, consists of 
dry scales from the surface of the skin. From all of the 
rest of the skin, little scales are constantly coming off. 

Suggestion to Teachers. — Illustrate this chapter by studies of the cuti- 
cle and hairs of men and animals, with a microscope. A lens of one-inch 
focus will show the pores on the palm. 



THE SKIN. 



157 



Papillae 



Sweat- 
gland. 



Fig. 59. 
Section of Skin. 



Epidermis 
or cuticle. 



They are much smaller than the scales of dandruff, and 
look like dust. "We do not notice them, but they gather 
in our clothing; and 



we may scrape off 
some of them, and 
examine them with 
a microscope. They 
appear as dry white 
scales or flakes, and 
they are really dead 
skin. As this dead 
surface wears off, the 
deep layer must keep 
on growing, to make 
up. 

4. The top layer of 
the skin is called the 
epidermis, or cuticle. 
The deep layer of the 
skin is called the 
derma, or cutis vera 
(true skin). If a very 
thin slice of skin be 
taken out by cut- 
ting straight down 
through it, and we 
look at it with a mi- 




Derma, or 

cutis vera. 



croscope, we see some- 
thing like the figure 
(Fig. 59). On the 
line which joins the 
derma and epidermis, there are little cones pointing up. 



158 



THE II UMAX BODY. 




Fig. 60. 
Papillje. 



These are called papillse, and are shown in larger size in 
Fig. 60, in which the epidermis has 
been stripped off, leaving only the 
derma with the papillae on its surface. 
In this way we sometimes scrape off 
the epidermis by an accident, and 
these papillae show as little red points. 
They contain blood - vessels and 
nerves. 

5. The palm of the hand, and especially the ends of 
the fingers, have distinct ridges, with furrows between 
them, which you can easily see. 
The ridges are made by the papil- 
lae, which are numerous in these 
parts. When magnified, they 
look like the figure (Fig. 61). 

6, The black spots on the 
ridges, in the figure, indicate the 
mouths of the sweat-ducts, which 
are called pores. In Fig. 59 we see 
one of these sweat-ducts. It is 
simply a tube. As we follow it 
down from the surface, it twists 
in corkscrew fashion through the 
cuticle, and then takes a wavy Fig. 6i. 
course through the cutis vera, and papillary ridges in the skin 

. • j • ji i i i r of the Palm. The Black Spots 

terminates m the deepest part of ABB THE PoRES . 

the skin, or just beneath it, in a 

coil, which is the sweat-gland. On the outside of this coil 

is a net-work of capillary vessels (Fig. 62). From these 

capillaries some of the water and salts of the blood pass 

through into the tube. As the tube fills, its contents well 




THE SKIN. 



159 



up, and flow over on the surface. The tubes are like 

springs, drawing their supply from 

the blood-vessels beneath. It has 

been estimated that there are 2,500,- 

000 of them altogether, and that, if 

they were all joined in one tube, it 

would be ten miles long. 

PERSPIRATION. 

7. We do not see any moisture on 
the surface when we are cool, but 
there always is some pouring out 
of the tubes. Ordinarily it changes 
into vapor, and is wafted away so 
fast that it can not gather in drops. 
But, when we are very warm, it 
wells up so rapidly that drops 
appear; and these sometimes flow in streams. If we 
remain quiet in a cool place, we dry off; that is, the per- 
spiration does not come so fast, and that which is already 
on the surface is changed to vapor, and carried away by 
the air. 

The moisture which is constantly coming from the 
pores, but which we can not see, is called insensible per- 
spiration. That which we can see and feel, as water, is 
called sensible perspiration, or sweat 




Fig. 62. 

Sweat-gland, with Capil- 
laries SURROUNDING IT. 



HAIR. 



8. Hairs grow from the skin. On most of the body 
they are short and fine. On the scalp and the face they 
grow long. The hair which covers the bodies of the 
lower animals is very useful in keeping them warm. 



160 



THE HUMAN BODY. 




Fig. 63. 
Section of the Skin, showing Roots of 
Hairs. — 1. Muscles attached to the hair- 
sac. 2. Sebaceous glauds. 



Man does not need it for this purpose, because he has 
intelligence to clothe himself. The head and throat are, 

however, protected in this 
way. In Fig. 63, we see 
the root of a hair as the 
microscope shows it. It is 
in the true skin, at the 
bottom of a tube. To the 
lower end of this tube, a 
muscular fiber is attached, 
which passes up to the 
surface of the skin. When 
this fiber contracts, it pulls 
up the hair, and makes the 
skin around it project, like a pimple. Cold makes these 
fibers contract : so does fear. It is in this way that the 
hair " stands on end," and that " goose-flesh " is made. 

SEBACEOUS GLANDS. 

9. Opening into the tubes in which the hairs stand, 
are other tubes, which come from little sacs, called seba- 
ceous glands. These lie in the skin, by the side of the 
hair-tubes. They manufacture an oily fluid, which is 
poured into the hair-tube, and out on the surface. It 
keeps the skin soft, and gives a moist and glossy appear- 
ance to the hair. When the scalp is unhealthy, and these 
glands are not active, the hair becomes harsh and dull 
and brittle. 

NAILS. 

10. The nails, like the hairs, grow from the skin. They 
are, indeed, a bit of the top layer, or cuticle, specially har- 
dened. It is desirable that the ends of the fingers should 



THE SKIN. 161 



be firm for picking and touching ; and, therefore, these 
little stiff backs are made to grow in them. The root of 
the nail is the upper end beneath the skin. The matrix 
is the bed on which it lies, and from which it grows. The 
nail may be shed or torn out, and, if the matrix is sound, 
a new nail will grow. If the whole matrix is destroyed, 
there will be no new one. But a very small portion of 
the matrix remaining, will produce a new nail, though it 
may be an imperfect one. 

USES OF THE SKIN. 

11. Understanding the structure of the skin, we are 
ready to notice its uses. 

1. It protects the parts beneath. Being tough and 
elastic, it can bear hard knocks. The cuticle, which is 
without nerves, covers and guards the sensitive parts. 
Neither fluids nor gases pass through it easily. If the 
skin is wdiole, we can safely put our hands in poisonous 
fluids, which would enter the blood, and do us harm, if it 
were scratched. 

2. It gives off waste matters from the body. Perspira- 
tion is chiefly w T ater, but it contains some other substances 
dissolved in it. The amount of water given off in a day 
is different at different times and in different persons, but 
is ordinarily about a quart. In this amount of water, two 
or three spoonfuls of solid matter are dissolved. 

3. It regulates the heat of the body. 

BODILY HEAT. 

12. Our bodies are always making heat ; and yet, if w T e 
put the bulb of a thermometer in the mouth of a healthy 
man, it will never rise more than a degree or two above 



162 THE HUMAN BODY. 

98 J° F. If it rises higher, he is sick, and has a fever. 
Nor will it fall more than a degree or two below 98J° F. 
In the stomach and in the blood, the thermometer would 
mark about 100° F., never rising much above, or falling 
much below. 100° F. is, then, the natural temperature 
of the inside of man's body. If he live under the tropi- 
cal sun, it will not rise more than a degree or two above 
this if he is well ; and, if he live in Greenland, it will 
not fall more than a degree or two below. 

13. If we undertake to keep a room at a fixed tempera- 
ture, we must have a fire to warm it ; and we must have 
means of cooling it if it is too warm. The human body 
has its fire, and it has its cooling-apparatus; and this 
heating and cooling apparatus is self- regulating, and 
works so perfectly, that, throughout a long life, in heat 
and in cold, the inward temperature never varies more 
than two or three degrees in health. 

HOW THE HEAT IS MADE EQUAL IN ALL PARTS. 

14. The fire is not in any one part, but in all parts. In 
every particle, the changes which take place, as the parti- 
cle takes up oxygen from the blood, and gives out car- 
bonic acid, make heat, as the changes which take place in 
the coal or wood in the stove make heat. This heat is 
given to the blood. It is warmer when it comes from 
the capillaries, where it has been in close contact with the 
particles ; and the blood, now divided in a thousand little 
streams, and again united in one stream, at the heart, 
diffuses the heat through the body. 

15. Suppose the feet, for example, to be more exposed 
to cold than other parts. The blood in the feet might be, 
for a very short time, colder than the rest of the body ; 



THE SKIN. 163 



but that blood immediately passes upward, and is warmed 
by the warmer stream above, with which it is mixed. A 
fresh supply of warm blood comes down, and contributes 
its heat to the feet. They are enabled in this way to 
maintain nearly the same heat as the rest of the body. 

On the other hand, suppose the brain or the stomach, 
while they are especially busy, to grow hotter than the 
rest of the body. Their heated blood is soon mingled with 
the general stream ; and, while it helps to heat the rest, is 
itself cooled. The heated parts are cooled by the cooler 
blood coming from other parts. So, by the constant cir- 
culation of the blood, the heat of all parts is made nearly 
equal. 

16. The air is ordinarily cooler than the body, and is 
constantly taking heat from it. Clothing keeps us from 
losing heat too fast. Furs and woolens have no warmth 
in themselves. They only keep off the cold air, and keep 
in the heat that the body makes. Besides this, in cold 
weather, we warm the air by fires. 

If we are much out of doors in cold weather, two things 
help us to keep warm : — 

i. We eat more, and so furnish more fuel to our inter- 
nal fires. We also get more oxygen in each breath, and 
this is fuel too. 

2. We exercise more, and that keeps these internal fires 
more active. 

In these ways, more heat is made ; and we can afford to 
lose more. 

HOW THE BODY IS COOLED. 

17. Sometimes there is too much heat in our bodies, 
as when we are exercising, or in the sun. It will not go 
off into the air fast enough, even if we are lightly clothed. 



164 THE HUMAN BODY. 

In that case, the skin becomes a cooling-apparatus. It 
works in two ways : — 

1. The deep layer of the skin is full of small blood- 
vessels. The effect of heat is to make these blood-vessels 
grow larger. The blood, then, flows into them, away from 
the deeper vessels. That is the reason your face gets red 
when you are heated. While the blood is in these vessels 
of the skin, it grows cool much faster than it does when it 
is deep in the body. It is nearer the cool air. The skin, 
then, receives more blood when we are heated, and spreads 
it out in a thin layer near the surface, and so cools it. By 
cooling the blood, the whole body is cooled. 

2. The two or three million sweat-glands do a most 
important part of the regulation of the heat of the body. 

In cities, water-carts go about in hot weather sprinkling 
the streets. This lays the dust, and cools the air. Much 
of the sprinkled water evaporates as it touches the warm 
stones ; and, wherever water evaporates, it makes things 
around it a little cooler. The sweat-glands form a great 
watering-apparatus for the surface of the skin. The per- 
spiration evaporates ; and the skin, and the blood in it, are 
cooled. The hotter it is, the more we perspire ; and, the 
more we perspire, the more heat is taken away. Men can 
stay for a time in a temperature of 200° F., and even more 
if they perspire freely. If perspiration is checked, they 
can not easily endure even a moderate heat. The reason 
why we suffer more from heat in what we call a " sticky 
day " in summer, is that the air is moist, and does not take 
up the moisture from the skin so fast as drier air would. 
Our bodies are wet, and evaporation goes on slowly. 

Suggestion to Teachers. — Show the cooling effect of evaporation by 
throwing a spray of alcohol or ether on the hand, with an atomizer. 



THE SKIN. 1G5 



CARE OF THE SKIN. 

Section II. — 1. If the skin of an animal is covered 
with varnish, it will soon die. If more than half of the 
surface of the skin is burned, even though the burn be 
not very deep, death will probably be the result. This 
shows how important the action of the skin is. It should 
be- well taken care of. 

2. To keep the skin healthy, three things are needed : — 

1. To keep the glands (sweat-glands and sebaceous 
glands) open and active. 

2. To keep the blood circulating freely in it. 

3. To let the air get to it. 

3. The solid matter in the perspiration, the oily matter 
from the sebaceous glands, and dead scales from the sur- 
face, together with dirt, will form a thin coating, which 
clogs the pores, and is itself unwholesome. 

The skin of a savage is freely exposed to air. The 
civilized man, stepping from a warm bed into warm 
clothing, and staying, perhaps, much of his time in close 
rooms, gets a soft, over-sensitive skin. Neither its glands 
nor its blood-vessels are vigorous, and it can not do its 
work well. 

4. Besides, such a man is liable to colds. A cold gen- 
erally comes from chilling some portion of the skin. 
Those who are out of doors in all weather do not often 
catch cold. Their skin, as well as the rest of the body, 
can better resist a chill. Those who are seldom exposed 
to cold air, and whose skin has become delicate, catch 
cold most readily. 

5. Too thick clothing keeps air from the skin, and 
weakens it by keeping it too warm. Air-baths are useful. 



166 THE HUMAN BODY. 

6. People who are sick or in pain, often receive great 
relief and comfort from having the skin rubbed; and 
it not only relieves, but, when thoroughly and perse- 
veringly done, it helps to cure many diseases. It is good 
for well people also. Thorough friction of the whole 
body with a brush or a dry towel every morning, is the 
next best thing to a daily bath. It exercises the muscles 
of the skin. It brings the blood into it. It removes the 
accumulations of dead cuticle and perspiration. 

7. No other one thing is so important for the health of 
the skin as bathing. It is possible for a delicate person 
to bathe too much, and imprudent bathing is sometimes 
hurtful. But, practiced with discretion, it is of great ad- 
vantage. True, very many people enjoy good health who 
never bathe. But it seems unnecessary to argue, that to 
keep the skin clean, the pores open, the glands active, and 
the circulation free, by water and rubbing combined, must 
make the skin, and therefore the whole body, more healthy. 

8. Cold water is a natural stimulant of the skin. The 
slight shock that it gives to the nervous system rouses the 
whole body to greater activity. Salt-water bathing is 
more invigorating than fresh-water bathing, because the 
salt has a direct, stimulating effect of its own. 

9. There is no other safeguard against colds so good as 
a daily bath. We take cold because the skin is sensitive 
and delicate, and will not bear exposure to the damp or 
chilly air. By regular bathing, it is made vigorous, the 
blood flows freely through it, and its nerves are strength- 
ened, so that we do not get chilled. 

For that very common affection, catarrh, cold water, 
used freely and regularly on the skin, is an excellent 
remedy. 



THE SKIN. 



167 



10. Certain cautions are to be observed in bathing : — 

1. Never bathe directly after a full meal. The blood 
is then directed to the stomach, and active work is 
going on there. Other organs are relaxed. The bath 
will hinder digestion, and sometimes cause an injurious 
shock. 

2. Never bathe in cold water when the system is greatly 
exhausted. Very delicate persons should not bathe in 
cold water at all. 

3. Be very cautious about bathing in cold water ivhen 
heated, especially if you are at the same time tired. 

4. Never stay in the water until you are chilled, so 
that you do not get warm soon on coming out, or until 
you feel languid and weak instead of feeling refreshed. 

Great injury sometimes results 
from neglect of these rules. 

THE EAR. 

Section III. — 1. The ear, 
like the nose, is partly outside, 
and partly inside, of the head. 
It may be divided into — 

The External Ear. 

The Middle Ear. 

The Internal Ear. 

2. The external ear is like an 
ear- trumpet; and its design is to 

collect the sound, and carry it in TmEAH.-i.1Lto of the external 
toward the internal ear, where ear - 2 - Parts of the kiddie ear. 

,-, n -. ... 3. Parts of the internal ear. 

the nerve ot hearing is. Like an 

ear-trumpet, it has an open part and a tube. The tube 

enters the head : the open part is on the outside. It is 




168 



THE HUMAN BODY, 



made chiefly of cartilage. There are three little muscles 
attached to the external ear, and some people can move 
it. Most people can not. 

3. The tube is called the external auditory canal. It 
is an inch long, and ends at the membrane of the tym- 
panum. 

4. The membrane of the tympanum, or drum-head, sepa- 
rates the middle from the external ear. The cavity of 
the middle ear is called the tympanum, or drum. It con- 
tains the small bones of the ear. It is connected with 
the back part of the throat by a tube, called the Eustachian 
tube. 

5. The internal ear is beyond the middle ear, deep in a 
bone of the skull. In it are the endings of the nerve of 
hearing. 

HOW WE HEAR. 

6. Sound is a vibration which can be perceived by 
the ear. Commonly as it reaches the ear it is a vibra- 
tion of the air. The waves of 
air enter the external auditory 
canal, and strike the drum- 
head. They make the drum- 
head vibrate. 

7. Across the cavity of the 
drum, from the drum-head to 
the opposite wall, the three 
little bones of the ear — the 
" hammer," the " anvil," and 
the " stirrup " — are stretched 
in a chain. The hammer is joined to the drum-head 
and to the anvil, and the anvil to the stirrup. 

8. When the drum-membrane vibrates, these little bones 




Fig. 65. 
Bones of the Left Ear, seen 
from the Inside. — 1. Hammer 
2. Anvil. 3. Stirrup. 4. Stapedius. 



THE SKIN. 169 



are made to vibrate. The last one in the chain, the stirrup, 
is joined to a small membrane in the inner wall of the 
drum, which is like a little drum-head. On the other side 
of this little drum-head is the inner ear, which is filled 
with water. As the stirrup vibrates, it sets the little 
drum-head vibrating; and that makes the water in the 
inner ear vibrate, and the little waves strike the ends of 
the nerve of hearing, and by it the impression is carried 
in to the brain. 

9. It is not the ear that hears. It is the brain that 
hears by means of the ear. 

7. An ear-ache is commonly caused by inflammation of 
the lining of the drum. It swells, and discharges a fluid 
that fills the cavity, and makes pain by pressure. Some- 
times, as the inflammation subsides, the fluid is absorbed. 
Sometimes the drum-membrane bursts, and lets out the 
fluid ; and the pain stops. A discharge from the ear com- 
monly comes from an inflamed middle ear through a hole 
in the drum-head. If the hole is small, it may heal up 
when the discharge stops. If a large part of the drum- 
membrane is gone, it will not heal up. 

8. The loss of the drum-head does not destroy the hear- 
ing, but it impairs it. 

9. Ear-ivax is made by glands in the skin lining the 
auditory canal. It is not a safe practice to dig it out with 
hair-pins or other instruments. Ear-wax is necessary to 
keep the canal and drum-head soft and moist, and it will 
take care of itself. If it forms hard lumps, and stops the 
ear, as it sometimes does, it may be removed by syringing 
with warm water. No one but a physician should put in 
any instrument. 



170 



THE HUMAN BODY. 




Fig. 66. 
The Eye. 



THE EYE. 

Section IV. — 1. The cavities in the skull which con- 
tain the eyes are called the orbits. They are shaped like 

pyramids, pointing inward, 
and are about an inch and 
a half deep. At the bottom 
of the orbits are holes, 
through which the nerves 
of the eye — the optic nerves 
— enter them. In the inner 
side of the orbits are open- 
ings into a canal, called the 
lachrymal canal, which runs 
straight down into the nose. 

2. The orbit is lined with fat, which makes a soft 
cushion for the eyeball. The eyeball is nearly round, 
and about an inch in diameter. It is attached to the 
optic nerve behind, as to a stem. 

3. The outer coat of the eyeball is white and tough. 
It is called the sclerotic coat. A transparent circle, like a 
watch-glass, is set into this in front. It is called the 
cornea. 

4. The cavity of the eyeball is divided into two cham- 
bers by the lens. The chamber behind the lens is filled 
with a jelly-like fluid, called the vitreous humor. The 
chamber before the lens is filled with a watery fluid, called 
the aqueous humor. 

The optic nerve goes to the interior of the ball, and 
spreads out, by dividing up into fine threads, to line the 
back part. This lining is the retina. 



Suggestion to Teachers. - 
sect it. 



- Get a beefs eye from the butcher's, and dis- 



THE SKIN. 



171 



5. Looking through the transparent cornea, we see the 
iris, the colored part. It is very smooth and beautiful. 
It is made partly of muscle fibers, 
of the kind not subject to the will. 
Some of them form circles around 
its center : others run from center 
to edge, like the spokes of a wheel. 
When these latter fibers contract, 
the hole in the center, called the 
pupil, grows large. When the cir- 
cular fibers contract, the pupil 
grows small. The iris is a cur- 
tain for the eye. Bright light 
makes it close up the pupil as 
much as possible. Opium and 
some other drugs will produce 
the same effect. Dim light makes 
it open the pupil. Belladonna 
produces the same effect. 

The contractions of the iris are 
good illustrations of reflex actions. 

6. The lids have each a thin 
plate of cartilage in them, to make them firm. The inside 
of each lid and the surface of the eye are covered with a 
mucous membrane, called the conjunctiva. The hairs 
(eyelashes) which grow from their edges help to protect the 
eye from dust and perspiration. Little sebaceous glands, 
called Meibomian glands, lie under the lining of the lids, 
and open on their edges. They oil the eyelashes and 
the edges of the lids. Under the roof of the outer part 
of the orbit, resting upon the eye-ball, is the tear-gland 
{lachrymal gland). About a dozen little ducts from it open 




Fig. 67. 
Section of the Front of the 
Eye. — 1. Sclerotic. 2. Cornea. 
3. Anterior chamber. 4. Pos- 
terior chamber. 5. Iris. 6. Lens. 



172 



THE HUMAN BODY. 




on the surface of the eye. This gland furnishes the 

moisture which the eye requires. 
By winking, the moisture is 
spread over the surface. 

7. Ordinarily moisture is sup- 
plied only as fast as it is needed, 
and it all evaporates. In strong 
feelings of sorrow or joy, moist- 
ure is poured out very rapidly, 
and gathers in tears. Xear the 
inner angle of the eye, an open- 
ing, apparently about as large 
as a needle, can be seen on the 
edge of each lid. These are 
Lach. the openings of the ducts which 

rymal gland. 2. Tear-passages. carry off ^ tearg They ^^ 

3. Lachrymal sac. 4. Nasal duct. y . ° 

into a sac in the inner corner 
of the orbit (the lachrymal sac) ; and that opens into the 
nasal duct, which runs through the lachrymal canal into 
the nose. When tears are very abundant, they overflow 
on the face. 

8. There are six muscles 
attached to the eyeball. 
One rolls it up, one clown, 
one out, one in, and two 
roll it on an axis passing 
from before backward. 



Fig. 68. 
Lachrymal Apparatus. - 




HOW WE SEE. 

9. The eye is like the 
camera with which a photographer takes pictures. 



Fig. 69. 2 
Muscles of the Eye-ball. — 1. Muscle 
of the upper lid. 2. Muscles of the ball. 
3. Optic nerve. 



The 



Suggestion to Teachers. — Show and describe the parts of a camera. 



THE SKIN. 173 



lens is like the glass lens in the end of the tube. The 
lining of the cavity of the eye-ball is colored dark, like 
the inside of the box of the camera. The retina is like 
the sensitive plate which the photographer puts in just 
before he takes the picture. The brain behind the eye 
is represented by the photographer himself looking 
through from behind his instrument, 

10. When we look at an object, a picture of it is made 
on the retina. ' This picture can be seen by a skillful ob- 
server looking into the eye with an instrument called an 
ophthalmoscope. It may be seen by looking from behind 
through an eye taken from an animal just killed, as the 
photographer looks through his camera. 

The retina, which is the ending of the optic nerve, 
carries in to the brain the impression which makes the 
picture. It is not the eye that sees. If the optic nerve is 
cut off, we do not see; although a picture will still be 
formed on the retina as before. It is the brain that sees. 
The eye is its instrument. 

CAUSES OF TROUBLE IN THE EYE. 

11. The eye is sometimes weak, and gets very tired 
and sore by use, simply because the whole body is weak. 
But generally when there is redness, swelling, or pain in 
the eye, there is something wrong in itself. It may be 
that the delicate lining of the lids, the conjunctiva, is 
inflamed, just as the lining of the throat is inflamed at 
times. The lids then feel rough, as if there were sand 
under them. 

TOO LONG SIGHT. 

12. One of the commonest causes of aching eyes and 
head, after reading, is too long sight. When we look at a 



174 THE HUMAN BODY. 

near object, the shape of the lens is changed a little by 
an effort of the eye. Too long-sighted eyes have to 
make more effort to do this than eyes with natural sight. 
The strain tires and irritates them, and may make them 
very weak. This trouble can be entirely relieved by 
glasses. 

TOO SHORT SIGHT. 

13. Short-sighted persons do not commonly have ach- 
ing and inflamed eyes. Their eyes do not have to make 
the effort that those of long-sighted people clo to see 
near objects. Reading does not tire them. But short- 
sightedness is liable to increase. It makes the vision of 
every thing more than a few feet away indistinct. It may 
be remedied by glasses, but they are an inconvenient 
necessity. 

14. Too short sight is very common among students. 
It is found, that, when children begin to go to school, few 
of them are short-sighted. In each higher class, there are 
more short-sighted pupils; and the number increases so 
fast, that we infer that there is something in the habits 
of school-children that makes them short-sighted. 

CAUSES OP TOO SHORT SIGHT. 

15. If we inquire what this cause of short sight is, we 
find that it is not any one thing, but many things. Every 
thing that tires and strains the eyes of school-children, 
tends to make them short-sighted. 

Causes of short sight are, — 

i. Too much use of the eyes. 

2. Bad light. 

8. Wrong positions when reading. 



THE SKIN. 175 



CARE OP THE EYES. 

16. l. If the eyes are tired and hot, it is a sign that 
they have been used too long. Stop until they are rested. 

2. Do not try to read when there is not light enough. 
If the light is dim, the book will be held too near the eyes. 
This tires them, and causes short sight. Reading by a 
fading twilight is particularly bad. 

s. The light should not be too glaring. If it is, the 
nerve is stimulated too much. This tires it. Besides, 
when any nerve is over-stimulated, it loses its sensitiveness 
after a time; and then the book will be held too near, and 
short-sightedness may result. 

For the same reason, the light should, if possible, fall 
over the left shoulder on the page. Then it will not be 
all reflected into the eyes, as when it comes from in front. 

4. The light should be steady. A flickering light keeps 
the eye annoyed, and tires it with constant changes. 

5. The book and the eye should be steady. It is as 
wearisome to the eye to have the page or the head in con- 
stant motion as to have the light flicker. Reading in the 
cars is trying to the eyes. 

6. The upright position is the natural and easy one for 
the eyes. To read when lying down, or with the head 
hanging over the book, tries the eyes, and tends to short- 
sightedness. 

7. Any serious trouble with the eyes should be attended 
to at once. It is better never to open a book than to lose 
the use of the eyes. If study can not be continued with- 
out ruining the eyes, abandon study. 



176 THE HUMAN BODY. 



COLOR-BLINDNESS. 

17. Not a few people are color-blind. Some can not dis- 
tinguish any colors. Others can not recognize a particular 
color, as red or blue, confounding it with other colors. If 
a person is color-blind, it is very desirable to know it. 
An engineer on a railroad, who could not tell a red light 
from a green one, would be a dangerous person. 



QUESTIONS. 

Section I. — 1. Name some qualities of the skin. 

2. What is a blister? Is the top layer of the skin sensitive? 
Are there any blood-vessels in the top layer? Are there any 
nerves or blood-vessels in the deep layer? 

3. What is dandruff? Is there any thing similar to it from the 
surface of the whole body ? 

4. What is the top layer of the skin called? What is the deep 
layer of the skin called? What are the papilla?, and where are 
they situated ? 

5. What makes the ridges and furrows on the skin of the palm ? 

6. What are the pores? Describe a sweat-duct. Describe a 
sweat-gland. Where does the sweat come from ? How does it get 
into the duct ? What is the estimated number of pores ? What is 
the estimated length of all the ducts combined? 

7. What is insensible perspiration? What is sensible perspira- 
tion ? 

8. What is the use of the hair ? What does it grow from ? How 
do the muscular fibers of the skin act on the hairs ? 

9. Where are the sebaceous glands, and what do they do? 

10. What is the use of the nails? What do they grow from? 
What is the root of the nail? What is the matrix of the nail? 
When a nail comes off, is it ever restored? When is it not restored? 

11. Name three uses of the skin. 

12. What is the natural heat of the inside of the body ? 



THE SKIN. 177 



13. How is it kept just at this temperature? 

14. What makes heat in the body? 

15. How is the temperature of the different parts kept equal? 

16. How do clothes keep the body warm ? In what two ways are 
we helped to resist the cold? 

17. Describe the first-named method in which the skin acts as a 
cooling-apparatus. Describe the second-named method in which 
the skin acts as a cooling-apparatus. How can men endure a tem- 
perature of 200° F. ? 

Section II. — 1. What shows the importance of the action of 
the skin ? 

2. What three things are necessary in order to keep the skin 
healthy? 

3. How does the skin become clogged and over-sensitive ? 

4. How may w T e become liable to colds ? 

5. What is the harm of too thick clothing ? 

6. What are the advantages of rubbing the skin ? 

7. What is the use of bathing? 

8. Why is cold-water bathing invigorating? 

9. What is the best safeguard against colds ? 

10. W r hat cautions are to be observed in bathing ? 

Section III. — 1. Name the three divisions of the ear. 

2. What is the use of the external ear? What is it made of? 

3. Describe the external auditory canal. 

4. What is the drum-head? What is the drum? Is the^e any 
opening out of the drum ? 

5. Where is the internal ear? What is its importance? 

6. What is sound ? 

7. W T hat is the position of the little bones in the ear? 

8. What is the use of the little bones ? How does the vibration 
reach the nerve of hearing? 

9. Does the ear hear? 

10. What frequently causes an ear-ache? From what spot does a 
discharge from the ear commonly come? Is a broken drum-head 
ever repaired ? 

11. Does the loss of the drum-head destroy hearing? 

12. W'hat is ear-wax? Is it safe to put instruments in the ear? 



178 THE HUMAN BODY. 

Section IV. — 1. Describe the orbits. 

2. State the shape, size, and position of the eyeball. 

3. What is the sclerotic coat of the eye? What is the cornea? 

4. What divides the eye into two chambers ? What fills the pos- 
terior chamber? What fills the anterior chamber? What is the 
retina ? 

5. Describe the iris. The pupil. What is the action of the iris ? 

6. What is the conjunctiva? What is the use of the eyelashes? 
What are the Meibomian glands? and what is their use? Where is 
the lachrymal gland ? What is its use ? 

7. What are tears? How are they carried off from the eye? 

8. What muscles move the eyeball? and how do they act? 

9. How does the eye resemble a photographer's camera? 

10. Where is a picture of the object looked at formed? Does 
the eye see ? 

11. Name some causes of trouble in the eye. 

12. What is the effect of too long sight? What is the remedy? 

13. What is the effect of too short sight ? 

14. Among what class is it most common ? 

15. What are causes of too short sight ? 

16. Give rules for the care of the eyes. 

17. What is color-blindness? 



APPENDIX 



APPENDIX. 



WHAT TO DO IN CASE OF ACCIDENT. 

It is natural to be alarmed when an accident occurs. Our 
feelings of sympathy for the sufferer, and perhaps of fear 
that he will die, agitate us, and scatter our wits, and make us 
helpless. The first thing at such a time, is to think. " What 
can I do? 1 ' is the question. To apply the mind vigorously 
to that question, is the best way to control the feelings. 

We can not anticipate all the particulars of accidents that 
may happen, but we can fix in the mind a few simple direc- 
tions for each kind. 

Painting. — When a person faints, the heart almost stops 
beating. The face is deadly pale. If we could see the brain, 
we should see that pale too. Because the blood is not sent to 
it in sufficient amount, it partly stops acting, and the person 
is unconscious. 

Place him on his back, with his head low. The blood will 
flow to the brain more easily in the horizontal than in the 
upright position. 

Give him air. Perhaps he has fainted because the air is 
bad. Fresh air will revive him. 

Sprinkle cold water on the face. It stimulates and rouses 
the nerves. 

181 



182 APPENDIX. 



Loosen the clothing about the neck and waist, so that it may 
be easy to breathe. 

A fainting-fit generally lasts only a short time. 

Fits. — In fainting, the face is pale, the pulse can hardly be 
felt, the limbs are limp and still. In fits, the face may be pale 
or red, the pulse can be felt easily, and the limbs often jerk 
and draw up spasmodically. Frothing at the mouth is not 
uncommon. If the fit is a long one, or if several come in 
succession, there will be time for the doctor to arrive. What 
you can do, is, — 

i, To keep the person from hurting himself in his struggles. 

2. To give him plenty of air. 

3. To see that there is nothing tight around his neck or chest. 

4. Place him w T ith his head raised a little. 

5. When he comes out of the fit, let him rest. 

Sunstroke. — This happens to those who have been ex- 
posed to great heat, either in the sunshine or in the shade. 
The face is flushed or pale, the pulse quick, and the skin dry 
and hot. 

Put the sufferer in as cool a place as possible, with his head 
raised, and apply cold water or ice to his head and chest. If 
he seems extremely weak, and the skin becomes cool, stop 
using ice, and put mustard and water on his feet and on the 
back of his neck. 

Shock. — Shock is the name given to the condition of pros- 
tration which sometimes follows a severe injury. The person 
is conscious, but extremely weak. The face is pale, the skin 
cool, and perhaps moist, the pulse quick and small, and there 
is restlessness. The powers may continue to fail until death 
comes. More frequently they rally after a time. 

A person in this condition must be handled very carefully. 
Any roughness may quench the spark of life. He must be 
laid down with his head low. Nature must be aided by 



APPENDIX. 183 



gentle stimulants. Heat is one of the best stimulants. Put 
hot-water bottles at his feet and sides. Give air, but avoid 
chilling him. Do not move him until he is better. 

Fractures and Dislocations. — A broken or dislocated 
limb is generally helpless. Even when there is no pain in 
it, it can not be used. If there is reason for thinking that 
such an accident has happened, the limb should be seen 
immediately by a doctor. In the mean time keep it per- 
fectly quiet. Do not allow the patient to attempt to use it. 
Support it in the position in which it is most comfortable. 
Bathe it in cold or hot water to relieve pain and keep down 
swelling. 

Bleeding. — When blood is flowing from a wound, it must 
be stopped. In most cases it is only necessary to press a 
handkerchief on it. This will check the flow so that the 
blood can coagulate in the vessels. Sometimes it is neces- 
sary to press hard upon the wound for a good while. Some- 
times this will not be sufficient. The blood is flowing, perhaps, 
from a large artery. Then a bandage must be drawn tight 
around the limb above the wound. If the bleeding stops, the 
bandage may be taken off in half an hour. If the bleeding 
does not stop, it is, perhaps, coming from a vein ; and a band- 
age must be tied around the limb below the wound. It may 
be necessary to find the course of the bleeding vessel, and press 
on it with the thumb. In some of these ways, external bleed- 
ing can always be checked for the time. 

Bleeding from the Nose. — Let the person keep upright, and 
hold his hands above his head. Apply cold to the back of 
the neck and to the forehead. Press on the nostrils. Push a 
little wad of cotton into the nostrils. 

Bleeding from the Lungs or Stomach or Bowels. — Keep the 
patient perfectly quiet on his back. Do not let him talk. 
Give him ice to swallow, and salt and water. 



184 APPENDIX. 



Poisoning. — If the poison has not been in the stomach 
more than an hour or two, try to make the patient vomit. 
This can sometimes be done by tickling the throat with the 
finger or a feather. If this is not sufficient, give a teaspoonful 
of mustard in a tumbler of lukewarm water. Or give a 
dose of ipecac. If the poison is causing pain in the stomach, 
give the whites of two or three eggs. If the poison is an acid 
(as sulphuric acid), give soapsuds or magnesia. If the poison 
is a narcotic, like opium or belladonna or chloral, keep the 
person from going to sleep. 

Drowning. — When a person, apparently drowned, is taken 
out of the water, his lungs have water in them, and his throat 
is stopped with water and mucus. Turn him on his face, and 
let the water run out of his mouth. Thrust your finger in 
his mouth, and clear it, and draw his tongue forward. Then 
lay him on his back, with a folded coat under his shoulders, 
raising them a little higher than his head. Tickle his nostrils 
with a feather. Give a little snuff, or a smell of smelling- 
salts. This may start his breathing. If it does not, try to 
make his chest expand and contract as it does naturally. A 
good way to do this is to stand across his body, or above his 
head, take hold of his arms, and bring his elbows up to the 
sides of his head. This opens the chest and lungs, and imi- 
tates the movement of inspiration. Then bring his arms 
down to his sides, and press them against the walls of the 
chest. This contracts the chest and lungs, and imitates the 
movement of expiration. Do this fifteen or twenty times in 
a minute for half an hour, if the chest does not begin to open 
and contract of itself in less time. At the same time, let 
others get off the wet clothing, and cover with dry. Let them 
rub the limbs vigorously, rubbing from the extremity toward 
the center. If bottles of hot water, or hot bricks or hot flan- 
nels, can be had, put them at his feet and sides. The three 
things to be aimed at, are, — 



APPENDIX. 185 



i. To start the movements of breathing. 

2. To restore warmth. 

3. To quicken the current of blood. 

Persevering and energetic efforts will often be rewarded by 
a return of the signs of life when they seemed to have gone 
forever. 

Remember that " a little knowledge is a dangerous thing " 
if it leads to undue self-confidence. In case of serious ac- 
cident, never fail to get help if possible from some one more 
experienced and capable than yourself. 



GLOSSARY. 



GLOSSARY. 



Ab-do'men. The belly. 

Ad'am's ap-ple. A prominence in 
the middle line of the neck. 

A-dul'ter-ate. To make impure by 
adding inferior substances. 

Al'i-ment. Nourishment. 

Al-i-ment'a-ry. Pertaining to ali- 
ment. 

A-nat'o-my. The science of the 
structure of organized bodies. 

A-or'ta. The great artery which 
comes from the heart, and passes 
down by the backbone. 

Ap-o-neu-r5'sis. A membrane of 
white fibrous tissue connected with 
a muscle. 

Ap'o-plex-y. A disease of the brain 
in which sense, and power of mo- 
tion, are suddenly lost. 

A'que-oiis. Watery. A term ap- 
plied to the fluid contents of the 
anterior chamber of the eyeball. 

Ath'lete (Lat., athleta, one who con- 
tends for a prize). One who espe- 
cially cultivates his muscles. 

Au'di-to-ry (Lat., auditus, hearing). 
Pertaining to the hearing. 

Au'ri-cle (Lat., auricula, a little ear). 
A name given to two of the cavities 
of the heart. 

Ax-il'la. The arm-pit. 

Bi'ceps (Lat., bis, caput, two-headed) 
A muscle extending from the shoul- 
der to the fore-arm, on the front of 



the arm. Also, a muscle extend- 
ing from the hip to the leg, on the 
back of the thigh. 

Brach'i-al (Lat., brachium, the arm). 
Pertaining to the arm. 

Bun'ion. An enlargement and in- 
flammation at the first joint of the 
great toe. 

Cap'il-la-ry (Lat., capillus, hair). 
Hairlike 

Ca-rot'id. A name applied to sev- 
eral arteries in the neck 

Car'pus. The wrist 

Car'ti-lage. Gristle 

Ca-tarrh'. An inflammation of the 
mucous membrane. 

Cau'da e-qul-na (horse's tail). The 
bundle of nerves into which the 
spinal cord divides at its lower end. 

Cer-e-bel'lum. A division of the 
brain, behind and beneath the cere- 
brum 

Cer'e-brum. The largest division 
of the brain. 

Chyle. The emulsion of fats made 
in the intestine. 

Chyme. The gruel-like mixture 
which passes from the stomach 
into the intestine in digestion. 

Clav'i-cle. The collar-bone. 

Co-ag-u-la/tion. The forming of 
clots 

Coc'cyx (Lat., coccyx, a cuckoo) A 
bone at the lower end of the 
189 



190 



GLOSSARY. 



backbone, shaped like a cuckoo's 
beak. 

Con-junc-ti'va. The mucous mem- 
brane covering the front of the eye- 
ball, and lining the lids. 

Con-vo-lu'tions. Ridges on the 
surface of the cerebrum and cere- 
bellum. 

Corn (Lat., cornu, a horn). A small 
portion of the epidermis, of horn- 
like hardness. 

Cor'ne-a (Lat., cornea, horny). The 
circular, transparent membrane in 
the front of the eye. 

Cor'pus-cle (Lat., corpusculum, a 
small body). A minute particle 

Cos'tal (Lat., costa, a rib). Pertain- 
ing to the ribs. 

Cu'ti-cle. The upper layer of the 
skin. 

Cu'tis ve'ra (true skin). The deep 
layer of the skin. 

Dan'druff. A scurf which forms 
on the scalp, and comes off in 
small scales. 

Den'tlne (Lat., dens, a tooth). A 
bonelike substance of which the 
teeth are made. 

Der'ma. The deep layer of the 
skin. 

Di'a-phragm (midriff) A sheet 
made of muscle and fibrous mem- 
brane between the chest and ab- 
domen. 

Duct. A tube by which a fluid, or 
other substance, is conducted. 

Dys-pep'si-a# Bad digestion. 

El'e-ment. One of the simplest 
parts of which any thing consists. 
A name applied to those simple 
substances, between sixty and sev- 
enty in number, to some of which 
all material objects can be re- 
duced. 

E-inul'sion. A mixture of oil with 



water containing some gummy or 
albuminous substance. 

En-am'el. The hard and polished 
substance which covers the crown 
of a tooth. 

Ep-i-derm'is. The upper layer of 
the skin. 

Eu-sta/chi-an tube. A tube con- 
necting the middle ear with the 
throat. 

Ex-prra-to-ry (Lat., ex spirare, to 
breathe out). Out-breathing. 

Fem'o-ral. Pertaining to the thigh. 

Fe'mur. The thigh-bone. 

Fi'ber. A thread of tissue. 

Fi-bro-car'ti-lage. A tissue made 
of cartilage, with white fibers 
mixed with it. 

Fi'brous mem'brane. A mem- 
brane made of fibers. 

Fib'u-la. A slender bone in the 
calf of the leg. 

Fla/vor. That which gives a pe- 
culiar odor or taste. 

Fos'sa (Lat., fossa, a ditch). A de- 
pression in a bone. 

Gas'tric. Pertaining to the stom- 
ach. 

Gas-troc-ne'mi-us. The large mus- 
cle extending from the thigh to the 
heel on the calf of the leg. 

Gland. A name applied to many 
organs which take part in the pro- 
cesses of life. 

Glob'ule. A little globe. 

Glot'tis. A slit in the membranous 
partition between the upper and 
lower parts of the larynx. 

Glii'ten. A substance in grain that 
contains the same chemical ele- 
ments that meat contains. 

Gly'co-gen. A substance formed in 
the body chiefly by the liver. . 

Ha-ver'sian ca-nals' (from Havers, 
who first described them). Micro- 



GLOSSARY. 



191 



scopic canals in bone, in which the 
blood-vessels run. 

Hu'me-riis. The arm-bone. 

Hy'gi-ene. The science of health. 

Hy'oid. U-shaped. 

In-spi'ra-to-ry (Lat. In spirare, to 
breathe in). In-breathing. 

I'ris (Lat., iris, the rainbow). A 
colored muscular membrane in the 
anterior chamber of the eye. 

Jaun'dice. A disease in which the 
body is colored yellow. 

Ju'gu-lar (Lax,., jur/idum, the neck). 
Pertaining to the neck. 

Lach'ry-mal (Lat., lacryma, a tear). 
Pertaining to tears. 

Lac'te-al (Lat., lac, milk). A term 
applied to the lymphatic ducts of 
the intestine. 

Lig'a-ment (Lat., ligare, to bind). 
A fibrous band that binds two parts 
(commonly bones) together. 

Lymph. The contents of the lym- 
phatic vessels. 

Mar'row. A soft substance con- 
tained in the cavities of bone. 

Ma/trix. An organ which produces 
or gives form to any thing. 

Me-dulla ob-lon-ga'ta. The low- 
est division of the brain. 

Mei-bo'mi-an. Discovered or de- 
scribed by Meibomius. 

Met-a-car'pus. The part of the 
hand between the wrist and the 
fingers. 

Met-a-tar'sus. The flat of the foot. 

Mi'tral. Like a miter, or bishop's 
cap. 

Mu'cous mem'brane. A mem- 
brane lining all the cavities of the 
body that are connected with the 
outer world. 

Mu'cus. The fluid which comes 
from the surface of the mucous 
membrane. 



Nar-cotlc. That which benumbs 
and stupefies. 

N a/sal. Pertaining to the nose. 

Nau'se-a. Sickness at the stomach 

Nfi'cle-us. In anatomy, a cell with- 
in a cell. 

OS-soph'a-gus. The gullet. 

Orbit. The bony cavity in which 
the eye is situated. 

Os in-nom-i-na'tum (nameless 
bone). The hip-bone. 

Pal-pi-ta/tion. A hard, rapid beat- 
ing of the heart. 

Pan'cre-as. An organ of digestion. 
The sweet-bread in calves. 

Pa-pilla. A conelike prominence 
of the skin or mucous membrane. 

Par'a-slte. A plant or animal that 
grows or lives on another. 

Pa-rotld. The name of a large 
gland under the ear. 

Pa-teTla. The knee-pan. 

Pec'to-ral (Lat., pectus, the breast). 
Pertaining to the breast. 

PePvis (Lat., a basin). The cavity 
inclosed by the hip-bones and the 
lower end of the backbone. 

Pep'sin. The active principle of the 
gastric juice. 

Per-i-car'di-um. A membranous 
bag inclosing the heart. 

Per-i-os'te-um. The membrane 
which covers bones. 

Phalanx. One of the small bones 
of the fingers and toes. 

Phar'ynx. The throat. 

Phys-i-oPo-gy. The science of the 
functions of organized bodies. 

Plas'ma. The watery part of the 
blood. 

Pleu'ra. A sac which covers the 
lung. 

Pons Va-rolii (bridge of Varolius). 
A division of the brain which con- 
nects the other main divisions. 



192 



GLOSSARY. 



P5re. The outlet of a sweat-duct. 

Proc'ess. A bony projection from 
a bone 

PuPmo-na-ry (Lat., pulmo. a lung). 
Pertaining to the lungs. 

Pu'pil. The central opening in the 
iris. 

Py-lo'rus. A muscular ring which 
surrounds the outlet of the stom- 
ach. 

Ra'di-al. Pertaining to the ra- 
dius. 

Ra'di-us. The outer bone of the 
fore-arm, 

Res-pi-ra'tion. The process by 
which oxygen is introduced into 
the blood, and carbonic-acid gas 
and vapor, and other matters, are 
discharged from it. 

Ret'i-na (Lat., rete, a net). The ter- 
minal fibers of the optic nerve lin- 
ing the back part of the eye. 

Sa'crum. A part of the backbone. 

Sa-li'va. Spittle. 

Sar-to'ri-us. A muscle extending 
from the hip to the leg, on the 
front of the thigh. 

Scap'u-la. The shoulder-blade. 

Scle-rot'ic (Lat., scleroticus, hard, 
firm). A term applied to the outer 
coat of the eye. 

Se-ba/ceous (Lat., sebaceus, tallowy). 
Applied to glands in the skin that 
produce a fatty fluid. 

Sem-i-lu'nar. Shaped like a half- 
moon. 

Sew'age. The contents of sewers. 

SkePe-ton. The framework of an 
organized body, of bone or other 
firm material. 

Skull. The bony frame of the 
head. 

Spi'nal ca-naP. The canal in the 
center of the backbone. 

Spi'nal coPumn. The backbone. 



Spi'nal cord. A cord of nerve- 
matter in the spinal canal. 

Sprain. An injury to the ligaments 
or tendons about a joint. 

Sta-pe'di-us. A very small muscle 
in the drum of the ear. 

Ster'num. The breast-bone. 

StmPu-lant (Lat., stimulus, a goad). 
That which goads or excites. 

Sub-cla'vi-an. Beneath the clavicle. 

Sub-lin'gual (Lat., sub lingua, un- 
der the tongue). The name of a 
salivary gland. 

Sub-max'il-la-ry (Lat., sub maxilla, 
under the jaw). The name of a 
salivary gland. 

Syn-5'vi-a. Joint-water. 

Syn-o'vi-al mem'brane. A thin 
membrane which lines the joint- 
cavity, and gives out the joint- 
water. 

Sys-tem'ic. Pertaining to the gen- 
eral system. 

Tape'worm. A worm that lives in 
the alimentary canal. 

Tar'sus. A portion of the foot be- 
tween the leg and the metatarsus. 

Ten'don. A cord of white, fibrous 
tissue connected with a muscle. 

Ten'don of A-chiPles. The ten- 
don of the gastrocnemius and so- 
leus muscles inserted in the heel. 
It was fabled that this was the only 
part in which Achilles was vul- 
nerable. 

Tho'rax. The chest. 

Tlb'i-a. The shin-bone. 

Tib'i-al. Pertaining to the tibia. 

Trans-fu'sion (Lat., trans, across, 
fundere, to pour). Pouring blood 
from the veins of one person into 
those of another. 

Tri-chT'na. A small worm that 
lives in the muscles of pigs, and of 
some other animals, and of men. 



GLOSSARY. 



193 



Tri-chi-no'sis. The disease caused 
by trichinae in the body. 

Tri-cus'pid. Three-pointed. 

Tym'pa-num (a drum). The middle 
ear. 

Urna. The inner bone of the fore- 
arm. 

Ul'nar. Pertaining to the ulna. 

Ven'tri-cle (Lat., ventriculvs, the 
belly) A name given to several 
small cavities in the body. 



Ver'te-bra (Lat., vertere, to turn). 
One of the bones which make the 
backbone. 

Vil'lus. A hairlike projection from 
the lining of the intestine. 

Vit're-oiis (Lat., vitreus, glassy). A 
term applied to the semi-fluid con- 
tents of the posterior chamber of 
the eyeball. 

Vo'cal cords. Two fibrous bands 
that form the margins of the glottis. 



INDEX. 



INDEX. 



Abdomen, 18, 132 
Absorption, 110 
Abstinence, 48. 
Acidity, 115. 
Adam's apple, 23, 130. 
Adulteration, 93. 
Air, 47, 52, 121, 122. 
" bad, 151. 
" polluted, 136, 
Air-cells, 130. 
Air-passages, 127. 
Alcohol, 48, 55, 73, 88, 92, 116, 151, 

" affinity for the brain, 153. 
after-effects of, 152. 

" how made, 92. 

" an irritant, 116. 

" effects on the gastric juice, 
117. 

" effects on the intestine, 117. 

" effects on the kidneys, 118. 

" effects on the liver, 118. 
Ale, 93. 

Alertness, 45, 46. 
Alimentary canal, 98. 

11 " divisions of, 100, 

110. 
Anatomy, definition of, 13, 14. 
Ankle, 27, 31. 
Aorta, 60, 64, 68. 
Aponeurosis, 41. 
Apoplexy, 74. 
Appetite, 87. 



Aqueduct-pipes, 87. 
Aqueous humor, 170. 
Arm, 23. 

Armies, feeding, 81. 
Arteries, 60, 61. 

" carotid, 69. 
" differ from veins, 70. 
" flow of blood in, 69. 
" strength of, 71. 
<v walls of, 72. 
Artery, axillary, 69. 
" brachial, 69. 
" femoral, 69. 
" pulmonary, 63, 71. 
" radial, 69. 
" subclavian, 69 
tibial, 69. 
ulnar, 69 
Athletes, 46, 48, 94. 
Auricles, 62. 
Auricle, right, 63. 
left, 64. 

Backbone, 19, 22, 53. 

" injury of, 143. 

Bathing, 166. 

" cautions, 167. 
Beans, 81. 
Beer, 93. 
Beets, 82. 

Beaumont, Dr., 116. 
Beef, 79. 

197 



198 



INDEX. 



Bicuspids, 103. 


Cabbages, 82. 


Bile, 108, 109- 


Cake, 83, 84, 85. 


Birds, blood-corpuscles of, 53. 


Camera, 172. 


Black Hole, 137. 


Canines, 103. 


Bleeding, 183. 


Capillaries, 60, 61, 64. 


Blister, 156. 


" flow of blood in, 67. 


Blood, 52. 


" walls of, 70. 


" a carrier, 110, 135. 


Carbon, 78. 


" impure, 55. 


Carbonic-acid gas, 122, 123, 134. 


" amount of, 55. 


Care of the eyes, 175. 


" loss of, 55. 


Carpus, 24. 


" color of, 54. 


Cartilage, 22, 32. 


" in murder-trials, 53. 


Catarrh, 166. 


" changes in color, 134. 


Cauda equina, 145. 


Blood-vessels, 60. 


Cavity of the skull, 17. 


* ' variations in size of, 72. 


" of the spinal column, 17. 


" enlargement of, 153. 


" of the trunk, 18. 


Blush, 73. 


Cerebrum, 143, 150. 


Bone, blood-vessels of, 29. 


Cerebellum, 143. 


" chemical composition of, 30. 


Chest, 131. 


" nerves of, 29. 


Chinese, mode of making tea, 89. 


" structure of, 28. 


Chloral, 94. 


Bones, number of, 19. 


Chyle, 101, 111. 


Bowels, 98. 


" absorption of, 112. 


Bow-legs, 30. 


Chyme, 111. 


Brain, 17. 


" absorption of, 112. 


" convolutions of, 144. 


Cider, 93, 94. 


" exercise of, 151. 


Circulation, organs of, 60. 


1 injury of, 143. 


Clavicle, 23. 


* gray matter of, 145. 


Close rooms, 151. 


" white matter of, 145. 


Clothing, 163. 


Brandy, 93. 


Coagulation, 54. 


Bread, 83, 84. 


Coccyx, 18, 19, 20. 


Breast-bone, 18, 22. 


Coffee, 89. 


Breath, amount of, 136. 


Colds, 129, 165, 166. 


" changes in, 136. 


Color-blindness, 176 


" contents of, 135. 


Collar-bones, 23. 


Breathing, involuntary, 133. 


Conjunctiva, 171. 


" process of, 131, 133. 


Convolutions, 144. 


Bright's disease, 118. 


Cookery, 85. 


Bronchi, structure of, 130. 


Cooking, 83. 


Bronchial tubes, 130. 


Cornea, 170. 


Bunion, 28. 


Corn, 81. 


Butter, 82, 101. 


" on the foot, 28. 


Buttermilk, 83. 


Corpuscles, red, 53. 



INDEX. 



199 



Corpuscles, white, 53. 54. 


Enamel of the teeth, 50, 104. 


Costal cartilages, 22. 




Endurance, 45, 46. 


Coughing, 149. 




Epidermis, 157. 


Crabs, 80. 




Epilepsy, 153. 


Cream, 83, 101. 




Eustachian tube, 168. 


Curves of the spine, 21 




Evaporation, 164. 


Cuticle, 157. 




Excitement, (^, 151. 


Cutis vera, 157. 




Excess in exercise, 47. 
Exercise for men, 46. 


Dandruff, 156. 




" for women, 46. 


Dentine, 104. 




" lack of, 116, 151. 


Derma, 157. 




law of, 44. 


Diaphragm, 61, 131. 




" regular, 46. 


Diet, ordinary, 79. 




Expression, 47. 


Digestion, 100 




Expiratory muscles, 132. 


" first act in, 


104. 


Eye, 170. 


" hinderances to, 115. 


" care of, 175. 


Digestive juices, 101. 




" trouble in, 173. 


Dislocations, 183. 




Eyeball, 170. 


Dissipation, 65. 




Eyelashes, 171. 


Drainage, 86. 






Drinkers, 152. 




Fainting, 55, 181. 


" stomachs of, 


117. 


Farmers, 44. 


Drowning, 184. 




Fat, 82, 101. 


Drowsiness, 51. 




Fatigue, 51, 115. 


Duct, nasal, 172. 




Femur, 26. 


" right lymphatic, 


112. 


Fermentation, 93. 


" thoracic, 112. 




Fibers, 43 


Ducts, 106. 




Fibro-cartilage, 20. 


" of sweat-glands, 158. 


Fibula, 26. 


Dyspepsia, 102. 




Fingers, 24. 
Fish, 80. 


Ear, 167. 




Fishes, breathing of, 125. 


" bones of, 168. 




Fits, 182. 


" drum of, 168. 




Flavors, 83. 


Earache, 169. 




Flesh, 40. 


Ear-wax, 169. 




Food, 52, 77, 98. 


Eating-habits, 87. 




" daily amount of, 88. 


Eating too fast, 115. 




" fried in fat, 84. 


" irregularity in, 


116. 


'* indigestible, 151. 


Eggs, 80. 




" too much, 115. 


Elbow, 31. 




Foot, 25. 


Elements, 77. 




" abuse of, 28. 


Elephant, 53. 




" divisions of, 27. 


Emulsion, 101, 109. 




Fore-arm, 23, 24. 



200 



INDEX. 



Fractures, 183. 


Heel, 27. 


Frogs, breathing of, 124. 


Hip, 25. 


Funny-bone, 145, 146, 


Hip-bone, 18, 25, 26. 




Hip-joint, 31. 


Game, 79. 


Humerus, 24. 


Gastric juice, 106. 


Hygiene, definition of, 14. 


Germs of disease, 86. 


Hyoid bone, 23. 


Gills, 125. 




Gin, 93. 


Ice-water, 115. 


Gin-drinkers' liver, 118. 


Incisors, 103. 


Glands, 100. 


Infant, 51,65, 79. 


" digestive, 110. 


Insanity, 153. 


" parotid, 105. 


Inspiratory muscles, 132. 


" salivary, 105. 


Instep, 27. 


" sebaceous, 160. 


Intestine, large, 99, 100. 


u sublingual, 105. 


Intestines, movements of, 40. 


" submaxillary, 105. 


small, 100. 


Glasses, 174. 


Intestinal juice, 109. 


Glottis, 138. 


Iris, 171. 


Gluten, 80. 




Glycogen, 108. 


Joints, 31, 32, 33. 


Goose-flesh, 160. 


Jaundice, 109. 


Graham flour, 81. 




Grasses, 78. 


Kidneys, alcohol in, 118. 


Greater circulation, 66. 


Knee-pan, 26. 


Greeks, 45. 




Gullet, 100. 


Lachrymal canal, 170. 




" gland, 171. 


Habits, 151. 


Lacteals, 101, 112, 114. 


Hair, 159. 


Lamb, 79. 


Hand, 23, 24, 25. 


Larynx, 130, 137. 


Harvey, William, 70. 


Lead pipes, 86. 


Haversian canals, 29. 


Lead-poisoning, 86. 


Head, injury of, 143. 


Leg, 25, 26. 


" number of bones in, 19. 


Length of life, 44. 


Hearing, organs of, 19. 


Lens, 170. 


Heat, bodily, 161, 162. 


Lesser circulation, 66. 


Heart, 61, 73. 


Levers, 17. 


Heart-beats in a minute, 65. 


Lids, 171. 


Heart, contractions of, 64, 66, 67. 


Ligaments, 24, 32, 33. 


" endurance of, 65. 


Liver, alcohol in, 118. 


" enlargement of, 47. 


•• work of, 108. 


" irritable, 65. 


Lobsters, 80. 


" rest of, 65. 


Long sight, 173. 


" sounds of, 67. 


Lower limb, divisions of, 25. 



INDEX. 



201 



Lower limbs, number of bones in, 19. 


Muscles, of the face, 47. 




Lung, appearance of, 127. 




11 shapes of, 41. 




Lungs, bleeding from, 47. 




Mustard, 88. 




44 structure of, 123, 125, 


126, 127. 


Mutton, 79. 




Lymph, 112, 113. 




t 




Lymphatic system, 112, 114. 




Nails, 160. 
Narcotics, 88. 




Marrow, 28. 




Nasal fossa?, 128. 




Matrix, 161. 




Nerve action, rate of, 148. 




Meat, 79. 




44 centers, 146. 




Medulla, 143. 




44 fibers. 147. 




Meibomian glands, 171. 




Nerve-cells, 147. 




Membranes of the brain and cord, 


Nerves, optic, i70. 




145. 




44 origin of, 145. 




Metacarpus, 24. 




of smell, 128. 




Metatarsus, 27. 




Nervousness, 151. 




Milk, 79, 82, 101. 




Nervous system, action of, 147 


150. 


Minerals, 85. 




Nitrogen, 78, 122. 




" absorption of, 112. 




Nose, 127, 128. 




Molars, 103. 




44 breathing through, 129. 




Mosquito, 149. 




Nucleus, 44, 53. 




Motor libers, 150. 








Mouth, 99, 100. 




Oats, 80, 81. 




Mucous membrane, 99. 




CEsophagus, 99, 100, 




Mumps, 105. 




Old age, death from, 51. 




Muscle, biceps, 41. 




Opium, 91, 92. 




44 contraction of, 42, 43 




Orbits. 170. 




44 effect of alcohol on, 


48. 


Os innominatum, 25. 




44 gastrocnemius, 41. 




Oxygen, 52, 123. 




44 heart, 04. 




44 in the blood, 134. 




44 involuntary, 40, 42, 43, 99. 


Oysters, 80. 




44 of alimentary canal 


101. 






44 pectoral, 41. 




Palm, 24. 




44 sartorius, 4 




Palpitation, 66. 




44 stapedius, 41. 




Pancreas, 109. 




44 voluntary, 42, 43. 




Pancreatic juice, 101, 109. 




44 weight of, 45. 




Papilla?, 158. 




Muscles, 40. 




Paralysis, 153. 




44 breathing, 50. 




Parasites, 79, 83. 




44 covering of, 41. 




Pastry, 83, 84. 




44 of digestive organs, 


50. 


Patella, 26. 




44 expiratory, 132. 




Pease, 81. 




44 inspiratory, 132. 




Pelvis, 18, 26. 




44 number of, 41. 




Pepper, 88. 




44 of the eye, 172 




Pepsin, 117. 





202 



INDEX. 



Pericardium, 61. 




Shaft of bone, 29. 


Periosteum, 29. 




Shell-fish, 80. 


Perspiration, 159, 161. 




Shin, 26. 


Phalanges, 24, 25, 27. 




Shock, 182. 


Pharynx, 1*00. 




Shoes, proper construction of, 28. 


Phosphate of lime, 30. 




Short sight, 174. 


Phosphorus, 78. 




Shoulder, 23. 


Physiology, definition of, 13, 14. 


Shoulder-blade, 23. 


Plants, 78, 79. 




Shrimps, 80. 


Plasma, 54. 




Silver, 78. 


Pleura, 133. 




Singing, 139. 


Poisoning, 184. 




Skeleton, 16, 30, 31. 


Pons Varolii, 143. 




Skin, 156. 


Pores, 158. 




" uses of, 161. 


Pork, 79. 




11 a cooling-apparatus, 164. 


Porter, 93. 




" care of, 165. 


Potato, 81. 




Skull, 19. 


Processes, 20. 




Sleep, 51, 52. 


Pulmonary circulation 


,66. 


" lack of, 151. 


Pulse, 71, 72. 




Sloth, the, 53. 


Pupil, 171. 




Smell, nerves of, 128. 


Pylorus, 107. 




" organs of, 19. 
" Smokers' heart," 90. 


Radius, 24. 




Sneezing, 149. 


Raw meat, 83. 




Snoring, 129. 


Reed-organ, 138. 




Speaking, 139. 


Reflex acts, 149, 171. 




Spice, 88. 


Repair, 51. 




Spine, 21. 


Reptiles, blood-corpuscles of, 53. 


Spinal canal, 18, 20. 


Respiration, 121. 




" column, 19. 


" principle 


of, 125. 


" cord, 18, 143, 145. 


Rest, 52. 




Sprain, 33. 


Retina, 170- 




Starch, 80, 81. 


Ribs, 22. 




Staying power, 46. 


Rice, 80. 




Sternum, 22. 


Right lymphatic duct, 


112. 


Stimulants, 45, 88, 151, 166. 


Rum, 93. 




St. Martin, 116. 
Stomach, 99. 


Sacrum, 19, 20. 




" changes in, 117. 


Saliva, 105. 




glands of, 106. 


Salt, 85. 




" location of, 106. 


Scapula, 23. 




Stoop, 21. 


Sclerotic, 170. 




Strength, 45, 46. 


Sensory fibers, 150. 




Students, 174 


Sewage, 8G. 




Sugar, 82. 



INDEX. 



203 



Sulphur, 78. 


Valve, mitral, 64. 


Sunstroke, 182. 


" tricuspid, 63. 


Sweat-glands, 158, 164. 


Valves, semilunar, 63, 64. 


Synovia, 32. 


Veal, 79. 


Synovial membrane, 32. 


Vegetables, 81. 


Systemic circulation, (36. 


Veins, 60, 61. 




" flow of blood in, 69. 


Tape-worm, 79, 83. 


11 jugular, 69. 


Tarsus, 27. 


" differ from arteries, 70. 


Taste, organs of, 19. 


" pulmonary, 63. 


Tea, 89. 


" strength of, 71. 


Tears, 172 


Vena cava inferior, 61. 


Teeth, 102, 103, 104. 


" " superior, 61. 


Tendons. 41. 


Ventilation, 137. 


Tendon of Achilles, 41. 


Ventricle, left, 64. 


Thigh, 25. 


Ventricles, 62. 


Thigh-bone, 26. 


Vertebrae, 19. 


Thorax, 18, 22. 


Villi, 111. 


Thoracic duct, 112. 


Vision, organs of, 19. 


Throat, 99, 100. 


Vitreous humor, 170. 


use of, 129. 


Vocal cords, 138. 


Thumb, 25. 


Voice, cultivation of, 138. 


Tibia, 26. 


" organs of, 137. 


Tiger, 103. 


Vomiting, 107. 


Tobacco, 48, 90. 




Tooth, structure of, 104. 


Waste, 51, 52. 


Trachea, structure of, 130. 


Water, 52, 85. 


Transfusion, 55. 


" absorption of, 112. 


Trichina, 83. 


" distilled, 85. 


Trichinosis, 83. 


" poisonous, 86. 


Tricuspid valve, 63. 


Wheat, 80. 


Trunk, number of bones in, 19. 


Whiskey, 93. 


Turnips, 82. 


Wines, 93. 


Tympanum, 168. 


Wine, adulteration of, 93. 




" home-made, 93. 


Ulceration, 116. 


Winking, 149. 


Ulna, 24. 


Worry, 151. 


Upper limb, divisions of, 23. 


Wound, 54, 70. 


" limbs, number of bones in, 19. 


Wrist, 24. 



